Class 11th Chemistry - Environmental Chemistry Case Study Questions and Answers 2022 - 2023 - by Study Materials - Sep 09, 2022 - View & Read

• 1)

  Environmental pollution is the effect of undesirable changes in our surroundings that have harmful effects on plants, animals and human beings. Even small amount of pollutants in air become significant. Some pollutants are biodegradable, e.g., discarded vegetables which rapidly break down by natural processes. DDT, plastic material, heavy metals, many chemicals, nuclear waste remain in environment for long time, are difficult to remove. Virus, bacteria cause diseases. Some of them are air borne. Some microorganisms get contaminated with water. Excessive use of fertilizers pesticides, insecticides cause soil pollution. Each household cleaning chemicals are harmful for children. Green chemistry can help to reduce pollution of air, water and soil.
  (a) When does rain become acid rain?
  (b) BOD, biological oxygen demand measure of organic material present in water. If BOD value is greater than 17 ppm what does it indicate? What is ideal value?
  (c) Why should jet aeroplanes not fly in stratosphere?
  (d) If there is enhance algae growth in water, what is its cause?
  (e) Which is more suitable for dry cleaning and why?

• 2)

  The table gives the tolerable limits up to which they are permitted in water according to international standards. Study the table and answer the questions based on table and related studied concepts.

  S.No	Chemical	Tolerable limit concentration
  1	F-	1 ppm
  2	Pb	50 ppm
  3	Zn	5 ppm
  4	Cu	3 ppm
  5	Fe	0.2 ppm
  6	Al	0.2 ppm
  7	Mn	0.05 ppm
  8	Cd	0.005 ppm
  9	\(\mathrm{SO}_{4}^{2-}\)	< 500 ppm
  10	\(\mathrm{NO}_{3}^{-}\)	50 ppm
  11	pH	5.5 to 9.5

  (a) Name two most harmful heavy metals present in water.
  (b) What is effect of higher cone  of \(\mathrm{SO}_{4}^{2-}\) ?
  (c) Which disease is caused by excess of \(\mathrm{NO}_{3}^{-}\) ?
  (d) What is use of F^- ions?
  (e) Which metal is safe among aU metals given in the table?
  (f) Is drinking distilled water good for health?
  (g) Which is better bleaching agent out of chlorine and H₂ O₂?

Class 11th Chemistry - Hydrocarbons Case Study Questions and Answers 2022 - 2023 - by Study Materials - Sep 09, 2022 - View & Read

• 1)

  Organic reactions can be classified into four main categories. Substitution reactions, addition reactions, elimination reactions and rearrangement reactions. Substitution reactions can be further classified into free radical, nucleophilic and electrophilic substitution reactions. Addition reactions can be nucleophilic as well as electrophilic addition reactions. Dehydration, dehydrohalogenation, dehalogenation are examples of elimination reactions. Conversion by ammonium cyanate to urea is an example of rearrangement reactions. Reactions are classified on the basis to nature of intermediate species formed. Mechanism of reaction is exact path followed by the reaction involving all steps showing intermediates and slowest steps of the reaction which is rate determining step. Oxidation, reduction, combustion reactions are also important in hydrocarbons.
  (a) Halogenation of alkane is an example of which type of reaction?
  (b) What happens when 2-methyl propane is heated with KMnO₄?
  (c) What type of reaction takes place when n-hexane is heated in presence of AICI₃ (anhy.) and HCI?CH2 =CH2 + KCI + HzO
  (d) What happens when but-2-yne reacts with H₂ in presence of Lindlar's catalyst.
  (e) CH₃CH₂C1 + KOH(alc) \(\longrightarrow\) CH₂ =CH₂ + KCI + H₂O 
  What is type of reaction?
  (f) Why do aromatic hydrocarbons undergo electrophilic substitution reaction?

• 2)

  Observe the table of variation of melting and boiling point in Alkanes. Study the table and answer the questions that follow based on table and related studied concepts.
  Variation of Melting Point and Boiling Point in Alkanes

  Molecular formula	Name	Molecular mass/u	b.p./(K)	m.p./(K)
  CH4	Methane	16	111.0	90.5
  C2H6	Ethane	30	184.4	101.0
  C3H8	Propane	44	230.9	85.3
  C4H10	Butane	58	272.4	134.6
  C4H10	2-Methylpropane	58	261.0	114.7
  C5H12	Pentane	72	309.1	143.3
  C5H12	2-Methylbutane	72	300.9	113.1
  C5H12	2,2-Dimethylpropane	72	282.5	256.4
  C6H14	Hexane	86	341.9	178.5
  C7H16	Heptane	100	371.4	182.4
  C5H18	Octane	114	398.7	216.2
  C9H20	Nonane	128	423.8	222.0
  C10H22	Decane	142	447.1	243.3
  C20H42	Eicosane	282	615.0	236.2

  (a) How does boiling point varies with the increase in carbon chain? Why?
  (b) Why does 2, 2-dimethyl propane has lower boiling point than 2-methyl butane and n-pentane?
  (c) Why is melting point of 2, 2-dimethyl propane is higher than n-pentane and 2-methyl butane?
  (d) What is physical state of heptane?
  (e) How does density vary with the increase in molar mass in hydrocarbons?
  (f) What is physical state of C₂₀H₄₂(Eicosane)?

• 3)

  Hydrocarbons are compounds of carbon and hydrogen only, obtained from coal and petroleum mainly which are major sources of energy. Hydrocarbons are classified as open chain, saturated (alkanes), unsaturated (alkenes and alkynes), cyclic (alicyclic) and aromatic based on structure.
  Alkanes show conformational isomerism due to free rotation along C-C bond leading to staggered and eclipsed conformations of ethane. Staggered conformation is more stable. Alkenes show geometrical (Cis-trans) isomerism due to restricted rotation around carbon-carbon double bond. Benzene and benzenoid show aromatic character. They follow Huckel rule \((4 n+2) \pi\) electrons which must be delocalised. The presence of activating and deactivating groups decide the position of electrophile after electrophilic substitution. Polynuclear fused aromatic hydrocarbons have carcinogenic property. Benzene is prepared by polymerisation of ethyne and by heating sodium benzoate with soda lime.
  (a) Why is staggered form of ethane more stable than eclipsed form?
  (b) Out of T-butene and 2-butene which will show geometrical isomerism.
  (c) Why is cis-2.-butene has higher boiling point than trans-2-butene?
  (d) Why is cyclopentadienyl anion is aromatic?
  (e) Why is -NO₂ group m-directing towards electrophilic substitution?
  (f) Convert acetylene to benzene .
  (g) Sodium benzoate, on heating with soda lime gives benzene, name the reaction.

Class 11th Chemistry - Organic Chemistry: Some Basic Principles and Techniques Case Study Questions and Answers 2022 - 2023 - by Study Materials - Sep 09, 2022 - View & Read

• 1)

  It is essential to purify an organic compound. The method used for purification depends upon nature of compound and impurity present in it. The common methods to purify a solid is sublimation and crystallisation. Crystallisation is most common method applicable to most of solid organic compounds. Liquids are purified by simple distillation, fractional distillation, distillation under reduced pressure, steam distillation. Differential extraction is used to extract organic compound from aqueous solution. Chromatography is used to separate coloured substances from plants. Column chromatography, thin layer chromatography and partition chromatography are types of chromatography used for isolation and purification of organic compounds.
  (a) Which method is used to purify camphor?
  (b) How is unwanted colour from organic compounds removed?
  (c) How is chloroform (Boiling point 334 K) and aniline (b.pt. 457 K) are separated? Why?
  (d) Which is condensed first in fractionating column, vapours of higher boiling point liquid or lower boiling point liquid?
  (e) How is glycerol purified?
  (f) How is Aniline purified? Why?
  (g) How are o-nitrophenol and p-nitrophenol separated? Why?

• 2)

  The order of decreasing priority of some functional groups is \(-\mathrm{COOH},-\mathrm{SO}_{3} \mathrm{H},-\mathrm{COOR},-\mathrm{COCl},-\mathrm{CONH}_{2}\), 
  
  Observe the table based on different functional groups and their respective prefix and suffix given below and answer the questions as follow.

  Functional Group	Prefix	Suffix
  Alkane	-	- ane
  Alkane	-	- ene
  Alkane	-	- yne
  -x	Halo (chloro, bromo, iodo)	-
  -OH	Hydroxy	- ol
  	Aldo or formyl	- al
  	Oxo	- one
  \(-\mathrm{C} \equiv \mathrm{N}\)	Cyano	nitrile
  -ROR	Alkoxy	ether
  -COOH	Carboxy	- oic acid
  -COOR	Alkoxy carbonyl	- oate
  -NH2	Amino	- amine
  -NO2	Nitro	-
  -CONH2	Carbamoyl or Amido	- amide
  -COX	Halo formyl	- oyl halide
  -SO3H	Sulpho	sulphonic acid

  (a) Write IUPAC Dame of HOCH₂ -(CH₂ )₃-CH₂COCH₃ .
  (b) What is IUPAC Dame of CH₂ =CH-CH₂Br. Give reason.
  (c) What is IUPAC name of 
   (i) 
   
  (ii) CH₂ =CH-CH=CH₂ 
  (d) Write structural formula of 6-methyl ectan-s-ol.
  (e) Write IUPAC name of
  (i) 
  
  (ii) 
  
  (f) Write IUPAC name of 
  
  (g) Write structural formula of cyclohex-2-en-1-ol.

• 3)

  Organic compounds are formed by covalent bonding. The nature of covalent bonding can described with the help of hybridisation, sp, Sp² and sp³. The structure and reactivity depends upon type of bonds present in organic compounds. Organic compound can be represented by various structural formulae, Wedge and Dash formula is 3-D representation. Organic compounds can be classified on the basis of functional groups. Organic reactions mechanism are based on structure of substrate and the attacking reagent.
  The intermediate formed can be free radical, carbocation, carbanion or carbene. The attacking reagent can be electrophile or nucleophile. The inductive, electromeric, resonance and hyper conjugative effect may help in polarisation of covalent bond. Organic reactions may be regarded as substitution, addition, elimination and rearrangement, oxidation and reduction reaction.
  After the compound is obtained in pure state, qualitative analysis helps to detect elements present in organic compounds whereas quantitative analysis helps to find percentage of various elements. Dumas and Kjeldahl method help to determine percentage of nitrogen, Carius method for halogens and sulphur. Carbon and hydrogen are estimated by the amount of CO₂ and H₂Oformed. Phosphorus estimation is done by oxidising it to H₃ PO₄, sulphur to H₂ SO₄ , The percentage of oxygen is determined by taking the difference of 100 and percentage of all elements. Empirical formula gives simple ratios of elements whereas molecular formula gives exact number of atoms of each element present in a compound.
  (a) What are free radicals?
  (b) Write the order of stability of carbocation.
  (c) An organic compounds has 8% sulphur. What is minimum molar mass of compound?
  (d) If C is 75%, H = 25%, what is molecular formula of compound?
  (e) In estimation of sulphur, which compound of sulphur is formed?
  (f) f Lassaigne extract of organic compound give blood-red colour with FeCI₃, what does it show?
  (g) Why should we add HNO₃ to Lassaigne extract before testing for halogens.

Class 11th Chemistry - The p-block Elements Case Study Questions and Answers 2022 - 2023 - by Study Materials - Sep 09, 2022 - View & Read

• 1)

  Group 13 and 14 are p-block elements, consisting of metals, non-metals and metalloids. These elements show variable oxidation st~tes, lower oxidation state becomes more stable, when we go down the group. The combined effect of size and availability of d-orbitals influence their ability to form \(\pi\) - bonds, Lighter elements form \(p \pi-p \pi\) bonds where as heavier elements form \(d \pi-p \pi \text { or } d \pi-d \pi\) bonds.
  Boron forms electron deficient compounds. AI exhibits +3 oxidation state. Tl+ is more stable than TI³⁺due to inert pair effect. Carbon is typical non-metal of group 14, shows a property of catenation and forms large number of compounds. It also shows allotropy, diamond, graphite and fullerene are crystalline allotropes of carbon. Group 14 elements show +4 and +2 oxidation states. Pb²⁺ is more stable than Pb⁴⁺.CO and CO₂ are oxides of carbon. CO2 is acidic and CO has lone pair, therefore, forms metal carbonyls. CO is deadly poisonous. CO₂ is greenhouse gas. Silica, silicates and silicones are important classes of compounds of silicon.
  (a) Why is Pb⁴⁺ good oxidising agent?
  (b) Why is CO deadly poisonous?
  (c) Why are silicones used in implants?
  (d) What is use of zeolites?
  (e) Why is fullerene purest allotrope of carbons?
  (f) What is structure of \(\mathrm{SiO}_{4}^{4}\) ?
  (g) Why is NaOH not stored in glass bottles?

• 2)

  Boron is element of Group 13. It is metalloid. Borax, orthoboric acid and diborane are important compounds of boron. Borax is used to prepared heat resistant pyrex glass. It is also used for cleaning metals like gold. It is also used in borax bead test to detect coloured salts in lab.
  Orthoboric acid is a weak acid used as antiseptic in eye lotion. It is solid having extensive H-bonding. It acts as Lewis acid.
  Diborane is a colourless, highly toxic gas. it catches fire spontaneously upon exposure to air. It burns in oxygen releasing enormous amount of energy.
  (a) Why is boric acid considered as weak Lewis acid?
  (b) What happens when boric acid is heated strongly?
  (c) What happens when sodium hydride reacts with B₂H₆?
  (d) What happens when sodium borohydride is reacted with I₂?
  (e) Give one use of NaBH₄.

• 3)

  Study the table of atomic and physical properties of group 14 elements and answer the questions that follow based on table and related studies concepts.
  Atomic and Physical Properties of Group 14 Elements

  Property		Element
  		Carbon C	Silicon Si	Germanium Ge	Tin Sn	Lead Pb
  Atomic number		6	14	32	50	82
  Atomic mass (g mol-1)		12.01	28.09	72.60	118.71	207.2
  Electronic configuration		[He]2s2 2p2	[Ne]3s 3p2	[Ar]3d104s24p2	[Kr]4d105s2 Sp2	[Xe]4f145d106s26p2
  Covalent radius/pma		77	118	122	140	146
  Ionic radius M4+/pmb		-	40	53	69	78
  Ionic radius M2+/pmb		-	-	73	118	119
  Ionization enthalpy/kJ mol-1	\(\Delta_{t} \mathbf{H}_{1}\) \(\Delta_{t} \mathbf{H}_{2}\) \(\Delta_{t} \mathbf{H}_{3}\) \(\Delta_{t} \mathbf{H}_{4}\)	1086 2352 4620 6220	786 1577 3228 4354	761	708 1411 2942 3929	715 1450 3081 4082
  				1537
  				3300
  				4409
  Electronegativityc		2.5	1.8	1.8	1.8	1.9
  Densityd/g cm3		3.51e	2.34	5.32	7.26f	11.34
  Melting point/K		4373	1693	1218	505	600
  Boiling point/K		-	3550	3123	2896	2024
  Electrical resistivity/ ohm em (293 K)		1014 -1016	50	50	10-5	2 x 10-5

  (a) Why does carbon not form C⁴⁺ ions?
  (b) Why is density of lead higher than Sn?
  (c) Why is melting point of TiD lowest in group 14?
  (d) Which is better conductor lead or Tin and why?
  (e) Why does \(\mathrm{CF}_{6}^{2}\) Dot formed but \(\mathrm{SiF}_{6}^{2-}\)exists?
  (f) Why is CO2 gas whereas Si02 solid?
  (g) What is carborundum? Give its use.

Class 11th Chemistry - The s-Block Elements Case Study Questions and Answers 2022 - 2023 - by Study Materials - Sep 09, 2022 - View & Read

• 1)

  Group 1 and group 2 elements are called s-block elements. Their general electronic configuration is ns^{1 to 2}. Group 1 are called alkali metals where as group 2 elements are called alkaline earth metals. They resemble with each other in many respects but differ in some of properties due to difference in valence electrons, electronic configuration and atomic size.
  (a) Why are group 1 elements softer than group 2 elements?
  (b) Why are group 1 elements more electropositive than group 2?
  (c) Why are K, Rb and Cs used in photoelectric cells?
  (d) Why is BeCI₂ more covalent than LiCI?
  (e) Which colour is imparted to flame by Ca²⁺and Ba²⁺?

• 2)

  Study the table and answer the questions based on the table and related studied concepts.
  Atomic and Physical Properties of the Alkaline Earth Metals

  Property	Beryllium Be	Magnesium Mg	Calcium Ca	Strontium Sr	Barium Ba	Radium Ra
  Atomic number	4	12	20	38	56	88
  Atomic mass (g mol-1)	9.01	24.31	40.08	87.62	137.33	226.03
  Electronic configuration	[He]2s2	[Ne]3s2	[Ar] 4s2	[Kr] 5s2	[Xe] 6s2	[Rn] 7s2
  Ionization enthalpy (I)/kJ mol-1	899	737	590	549	503	509
  Ionization enthalpy (II)/kJ mol-1	1757	1450	1145	1064	965	979
  Hydration enthalpy (kJ/mol)	- 2494	-1921	-1577	-1443	-1305	-
  Metallic radius/pm	111	160	197	215	222	-
  Ionic radius M2+/pm	31	72	100	118	135	148
  m.p./K	1560	924	1124	1062	1002	973
  b.p/K	2745	1363	1767	1655	2078	(1973)
  Density / g cm-3	1.84	1.74	1.55	2.63	3.59	(5.5)
  Standard potential \(\mathbf{E}^{\odot} / \mathbf{V}\) for (M2+/ M)	-1.97	-2.36	-2.84	-2.89	- 2.92	-2.92
  Occurrence in lithosphere	2*	2.76**	4.6**	384*	390*	10-6*

  (a) Which is best non-radioactive reducing agent in Group 2? Why?
  (b) Why does hydration enthalpy of bivalent cations of group 2 decrease down the group?
  (c) Which element of group 2 has lowest melting points and why?
  (d) Name a radioactive element of group 2
  (e) Which group 2 element has lowest density?

• 3)

  The first element of each group, lithium in first group and beryllium in the second group differ from rest of the elements but have similar properties to diagonally situated elements. Lithium resembles with Mg and Be resembles with Aluminium. Boron resembles with Silicon.
  The compounds of alkali metals are predominantly ionic. The oxides and hydroxides are soluble in water forming strong alkalies. Important compounds of sodium includes sodium carbonate, sodium chloride, sodium hydroxide and NaHCO₃ Sodium hydroxide is manufactured by Castner-Kellner process and sodium carbonate by Solvay process.
  The oxides and hydroxides of group 2 elements are less basic than group 1, oxides and hydroxides. CaO, Ca(OH)₂, \(\mathrm{CaSO}_{4} \cdot \frac{1}{2} \mathrm{H}_{2} \mathrm{O}, \mathrm{CaCO}_{3}\) and cement are industrially important compounds. Portland cement is an important 2 constructional material. It is manufactured by heating limestone and clay in a rotary kiln. The clinker obtained is mixed with 2 to 3% gypsum.
  Na⁺,K⁺, Mg²⁺and Ca²⁺ are found in large amounts in biological fluids. These ions perform important biological functions such as maintenance of ion balance and nerve impulse conductions.
  (a) What is cause of diagonal relationship?
  (b) Why does first element of each group differ from rest of the elements?
  (c) Name the product formed at anode and cathode on electrolysis of brine solution
  (d) Why is BeSO₄ soluble in water but BaSO₄ in not?
  (e) Why is gypsum is added to cement?
  (f) What is role of Ca^{2 +} in our body?
  (g) What is role of Na⁺ in blood plasma?

Class 11th Chemistry - Hydrogen Case Study Questions and Answers 2022 - 2023 - by Study Materials - Sep 09, 2022 - View & Read

• 1)

  Hydrogen is most abundant element in universe. It exist in combined state in form of H₂ O. On industrial scale, it is prepared by water gas shift reaction from petrochemicals. It is also obtained as a by-product of the electrolysis of brine. It has high bond dissociation enthalpy due to which it is less reactive. It forms hydrides with almost all elements. The hydrides are of three types, ionic, covalent and metallic or non-stoichiometric hydrides. It acts as reducing as well as oxidising agent. Its compound H₂ O is essential for life. H₂ O₂ acts as oxidising, bleaching, as well reducing agent. D₂ O(Heavy water is used as coolant in nuclear reactors).
  (a) A 5.0 cm³ solution of H₂ O₂ liberates 0.508 g of iodine from KI solution. Calculate the strength of H₂ O₂ solution in terms of volume strength at STP.
  (b) What is volume of oxygen liberated at STP from 15 mL of 20 vol. of H₂ O₂ of STP.
  (c) How is water gas produced?
  (d) What happens when steam is passed over water gas in presence of catalyst in water gas shift reaction.
  The molecular formula of commercial resin used for exchange in water softening is C₈H₇SO₃Na(Mol. Wt-206). What would be maximum uptake of Ca^{2 +} ions by resin in mol per gram of resin?
  (f) Write ionic reduction of H₂O₂ when it acts as reducing agent in basic medium.
  What is false about H₂O₂?
  (a) Acts as both oxidising as well as reducing agent
  (b) Both OH bonds lie in same plane
  (c) Pale blue liquid.
  (d) Can be reduced by O₃.

• 2)

  Study the table and answer the questions that follow based in this table and related studied concepts.
  Physical Properties of H₂O and D₂ O.

  Property	H2O	D2 O
  Molecular mass (g mol-1)	18.0151	20.0276
  Melting point/K	273.0	276.8
  Boiling point/K	373.0	374.4
  Enthalpy of formation/kJ mol-1	-285.9	-294.6
  Enthalpy of vaporisation (373K)/kJ mol-1	40.66	41.61
  Enthalpy of fusion/kJ mol-1	6.01	-
  Temp of max. density/K	276.98	284.2
  Density (298K)/g cm-3	1.0000	1.1059
  Viscosity/centipoise	0.8903	1.107
  Dielectric constaat/C2/N .m2	78.39	78.06
  Electrical conductivity (293K/ohm-1 cm-1 )	5.7x 10-8	-

  (a) At what temperature heavy water has maximum density?
  (b) What is use of heavy water?
  (c) Why is water responsible for moderation of climate and body temperature of living beings?
  (d) Why is boiling point of D₂ O higher than H₂O?
  (e) What happens when Mg₃N₂ reacts with D₂O?
  (f) What is the formula of Deuterium sulphate?
  (g) What happens when aluminium carbide reacts with water?

Class 11th Chemistry - Redox Reactions Case Study Questions and Answers 2022 - 2023 - by Study Materials - Sep 09, 2022 - View & Read

• 1)

  Redox reactions are reactions in which oxidation and reduction takes place simultaneously. Oxidation number are assigned in accordance with the set of rules. Oxidation number and ion electron methods both are used in balancing ionic equations. Redox reactions are classified as combination, decomposition, displacement and disproportionation reactions. The concept of redox couple and electrode processes is basis of electrolysis and electrochemical cells.
  (a) What are oxidation number of each individual Br in Br₃ O₈ ?
  (b) If electrolysis of CuSO₄ solution is carried out using Cu electrodes, what will be reaction taking place at anode.
  (c) What is oxidation number of Cr in CrO₅?
  (d) Give one example of disproportionation reaction.

• 2)

  Redox reactions are important class of reactions which are taking place in our daily life. Metals are good reducing agents because they can lose electrons easily whereas non-metals are good oxidising agents which can gain electrons easily. In electrolytic cells, electricity is passed to bring about redox reaction. All rechargeable batteries act as electrolytic cells while recharging. Electrochemical cells produce electricity as a result of redox reaction. Salt bridge is used in electrochemical cell to complete internal circuit and prevents accumulation of charges.
  (a) What is electrochemical cell?
  (b) Why is anode called oxidation electrode?
  (c) Give one example of rechargeable cells widely used in vehicles.
  (d) Highly reactive metals are obtained by electrolysis of their molten ores, why?
  (e) What is direction of flow of current and electrons?
  (f) What is standard electrode potential?
  (g) What is meaning of -ve value of reduction potential? Give example.

• 3)

  The standard electrode potentials at 298 K
  Ions are present as aqueous species and H ₂O as liquid; gases and solids are shown by g and s respectively.

  	Reaction (Oxidised form + ne- \(\rightarrow\) Reduced form)		\(\mathbf{E}^{\odot} / \mathbf{V}\)
  	\(\mathbf{F}_{2}(g)+2 e^{-} \longrightarrow 2 \mathbf{F}\) \(\mathrm{Co}^{3+}+e^{-} \longrightarrow \mathrm{Co}^{2+}\) \(\mathbf{H}_{2} \mathbf{O}_{2}+\mathbf{2} \mathbf{H}^{+}+\mathbf{2} e^{-} \longrightarrow \mathbf{2} \mathbf{H}_{2} \mathbf{O}\) \(\mathrm{MnO}_{4}^{-}+8 \mathrm{H}^{+}+5 e^{-} \longrightarrow \mathrm{Mn}^{2+}+4 \mathrm{H}_{2} \mathrm{O}\) \(\mathbf{A u}^{3+}+\mathbf{3} \boldsymbol{e}^{-} \longrightarrow \mathbf{A u}(s)\) \(\mathrm{Cl}_{2}(g)+2 e^{-} \longrightarrow 2 \mathrm{Cl}^{-}\) \(\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}+\mathbf{1 4 H}^{+}+6 e^{-} \longrightarrow 2 \mathrm{Cr}^{3+}+7 \mathrm{H}_{2} \mathrm{O}\) \(\mathrm{O}_{2}(\mathrm{~g})+4 \mathrm{H}^{+}+4 e^{-} \longrightarrow 2 \mathrm{H}_{2} \mathrm{O}\) \(\mathrm{MnO}_{2}(s)+4 \mathrm{H}^{+}+2 e^{-} \longrightarrow \mathrm{Mn}^{2+}+2 \mathrm{H}_{2} \mathrm{O}\) \(\mathbf{B r}_{2}+2 e^{-} \longrightarrow 2 \mathbf{B r}^{-}\) \(\mathrm{NO}_{3}^{-}+4 \mathrm{H}^{+}+3 e^{-} \longrightarrow \mathrm{NO}+\underline{2} \mathrm{H}_{2} \mathrm{O}\) \(2 \mathrm{Hg}^{2+}+2 e^{-} \longrightarrow \mathrm{Hg}_{2}^{2+}\) \(\mathbf{A g}^{+}+\boldsymbol{e}^{-} \longrightarrow \mathbf{A g}(\boldsymbol{s})\) \(\mathbf{F e}^{3+}+e^{-} \longrightarrow \mathbf{F e}^{2+}\) \(\mathrm{O}_{2}(g)+2 \mathrm{H}^{+}+2 e^{-} \longrightarrow \mathbf{H}_{2} \mathrm{O}_{2}\) \(\mathbf{I}_{2}(s)+2 e^{-} \longrightarrow 2 \mathbf{I}^{-}\) \(\mathbf{C u}^{+}+e^{-} \longrightarrow \mathbf{C u}(\boldsymbol{s})\) \(\mathrm{Cu}^{2+}+2 e=\mathrm{Cu}(s)\) \(\mathbf{A g C l}(s)+e^{-} \longrightarrow \mathbf{A g}(s)+\mathbf{C l}\) \(\mathbf{A g B r}(s)+e^{-} \longrightarrow \mathbf{A g}(s)+\mathbf{B r}^{-}\) \(2 \mathrm{H}^{+}+2 e^{-} \longrightarrow \mathbf{H}_{2}(g)\) \(\mathbf{P b}^{2+}+2 e^{-} \longrightarrow \mathbf{P b}(s)\) \(\mathrm{Sn}^{2+}+2 e^{-} \longrightarrow \operatorname{Sn}(s)\)\(\)\(\) \(\)\(\mathbf{N i}^{2+}+2 e^{-} \longrightarrow \mathbf{N i}(s)\) \(\)\(\mathrm{Fe}^{2+}+2 e-\mathrm{Fe}(s)\) \(\)\(\mathrm{Cr}^{3+}+3 e^{-} \longrightarrow \mathrm{Cr}(s)\) \(\)\(\mathbf{Z n}^{2+}+2 e^{-} \longrightarrow \mathbf{Z n}(s)\) \(\)\(\mathbf{2} \mathbf{H}_{2} \mathbf{O}+\mathbf{2} e^{-} \longrightarrow \mathbf{H}_{2}+\mathbf{2} \mathbf{O H}^{-}\) \(\)\(\mathbf{A l}^{3+}+\mathbf{3 e}^{-} \longrightarrow \mathbf{A l}(\boldsymbol{s})\) \(\)\(\mathbf{M g}^{2+}+2 e^{-} \longrightarrow \mathbf{M g}(s)\) \(\)\(\)\(\mathrm{Na}^{+}+e^{-} \longrightarrow \mathrm{Na}(s)\) \(\mathrm{Ca}^{2+}+2 e^{-} \longrightarrow \mathrm{Ca}(s)\) \(\mathbf{K}^{+}+e^{-} \longrightarrow \mathbf{K}(\boldsymbol{s})\) \(\mathbf{L i}^{+}+e^{-} \longrightarrow \mathbf{L i}(s)\)		2.87
  			1.81
  			1.78
  			1.51
  			1.40
  			1.36
  			1.33
  			1.23
  			1.23
  			1.09
  			0.97
  			0.92
  			0.80
  			0.77
  			0.68
  			0.54
  			0.52
  			0.34
  			0.22
  			0.10
  			0.00
  			0.13
  			0.14
  			0.25
  			0.44
  			0.74
  			0.76
  			0.83
  			1.66
  			2.36
  			2.71
  			2.87
  			2.93
  			3.05

  1. A negative \(\boldsymbol{E}^{\ominus}\) means that the redox couple is a stronger reducing agent than the H⁺/H₂ couple.
  2. A positive \(\boldsymbol{E}^{\ominus} \) means that the redox couple is a weaker reducing agent than the H⁺/H₂ couple.
  (a) Which is best oxidising agent and why?
  (b) Which is best reducing agent and why?
  (c) Calculate \(\mathbf{E}^{\circ} \text { cell }\) lof Zn(s)/Zn²⁺(1M) II Cu^{2 +}(aq)/Cu(s).
  (d) If a redox couple has negative E^o, is it stronger or weaker reducing agent than H⁺/H₂ couple?
  (e) Arrange K, Ag, Hg, Mg, Cr in increasing order of reducing power.
  (f) Arrange AI, Cu, Fe, Mg and Zn in order in which they will displace each other from salt solution.

Class 11th Chemistry - Equilibrium Case Study Questions and Answers 2022 - 2023 - by Study Materials - Sep 09, 2022 - View & Read

• 1)

  Equilibrium can be established for both physical and chemical processes and at equilibrium rate of forward and reverse processes are equal. Equilibrium constant (K_c) is expressed as the concentration of products divided by reactants, each raised to Stoichiometric Coefficient. K_c has fixed value of constant temperature and at this stage concentration, pressure, etc. become constant. K_p is equilibrium constant in terms of partial pressure of gases or vapours. The direction of reaction can be predicted by reaction quotient Q_c and Q_p Q_c = K_c at equilibrium and Q_p = K_p Le Chatelier's principle states 'Equilibrium' will shift in the direction so as to counter balance the effect of change in T, P and conc. The equilibrium between ions and unionised molecules in weak electrolyte is called ionic equilibrium.
  (a) At a certain temperature Kc = \(\frac{9}{4}\) for the reaction:
  CO(g) + H₂O(g) \(\rightleftharpoons\) CO₂ (g) + H₂ (g)
  If we take 10 moles of each of four gases in one litre container, what will be concentration of H2 at equilibrium?
  (b) In the equilibrium CO(g) + H₂O(g) \(\rightleftharpoons\) CO₂ (g) + H₂ (g) if at a given temperature, the concentration of the reactants are increased, what will be the value of equilibrium constant K_c.
  (c) If the value of an equilibrium constant for a particular reaction is 1.6 x 10¹², what will be present in the system at equilibrium.
  (d) The K_sp of AgCl, AgBr, AgI are 1.8 x 10^-10 , 5.0 x 10^-13 , 8.3 x 10^-17 , which will precipitate last if AgNO₃ solution is added to NaCI, NaBr. NaI?
  (e) The equilibrium constant for reaction N₂ (g) + 3H₂ (g) \(\stackrel{K_{1}}{\rightleftharpoons}\) 2NH₃(g) is 49, what is equilibrium constantfor NH₃(g) \(\stackrel{\mathbf{K}_{2}}{\rightleftharpoons} \frac{1}{2} \) N₂(g) + \(\frac{3}{2}\) H₂(g)?

• 2)

  Observe the table of the ionisation constants of some common polyprotic acid at 298 K. Answer the questions based on this table and related studied concepts.
  The Ionisatlon Constants of Some Common Polyprotic Acids (298K)

  Acid	Ka1	Ka2	Ka3
  Oxalic acid	5.9 x 10-2	6.4 x 10-5
  Ascorbic acid	7.4 x 10-4	1.6 x 10-12
  Sulphurous acid	1.7 x 10-2	6.4 x 10-11
  Sulphuric acid	Very large	1.2 x 10-2
  Carbonic acid	4.3 x 10-7	5.6 x 10-11
  Citric acid	7.4 x 10-4	1.7 x 10-5	4.0 x 10-7
  Phosphoric acid	7.5 x 10-3	6.2 x 10-11	4.2 x 10-13

  (a) Why is K_a1 greater than K_a2?
  (b) Arrange K_a1, K_a2 and K_a3 in phosphoric acid.
  (c) Why is K_a1 >>> K_a2 in sulphuric acid?
  (d) What is relationship between K_a1, K,_a2 and K_a3?
  (e) Write expression for K_a1 and K_a2 and K_a of H₂CO₃
  (f) What is basicity of H₃ PO₄?
  (g) Out of oxalic acid and citric acid, which is stronger?

• 3)

  Arrhenius acids give W ion in aqueous solution where as bases give OIr in aqueous solution. Bronsted acids are proton donor where as Bronsted bases are proton acceptors. Acids, on donating proton form conjugate base where as bases form conjugate acid after accepting proton. Buffer solution is a solution whose pH does not change by adding small amount of H⁺ or OH^-. The decrease in conc. of one of the ion by adding other ions as common ion is called common ion effect. Lewis acids are electron deficient or +vely charged. Lewis bases are electron rich or negatively charged, K^sp (solubility product) is the product of molar concentration of ions raised to power number of ions per formula of the compound in sparingly soluble salt. Precipitation occurs only if ionic product exceeds solubility product. Solubility of salt decreases in presence of common ion. K_W, is ionic product of water, 1 x 10^-14 at 298 K. K^W, increases with increase in temperature. pH is -log [H₃O₊] where [H³O⁺] = C\(\alpha\) in monoprotic acid 'C' is molar cone.,'\(\alpha\)' is degree of ionisation. A salt is said to be hydrolysed if pH of solution changes. K_H is hydrolytic constant. pH of salts of strong acid and strong base is equal to 7. pH of other salts can be 7. pH of buffer solution can be calculated with the help of Henderson equation.
  pH = pKa + \(\log \frac{[\text { Salt }]}{[\text { Acid }]}\) 
  (a) What win be conjugate base of
  (i) H₂ SO₄
  (ii) H\(\mathbf{C}{O}_{3}^{-}\)\(\)?
  (b) What are conjugate acids of 
  (i) \(\mathbf{N H}_{2}^{-}\) 
  (ii) NH₃
  (c) The conc. of [H₃O⁺] is 4 x 10^-4. What is pH of solution? [log 4 = 0.6021], log 10 = 1.
  (d) K_b for NH₃ is 1.80 x 10^-5 .What will be Ka? [K_W = 1 x 10^-14]
  (e) K_sp of BaSO₄ is 1.0 x 10^-10. What is its solubility?
  (f) ) Calculate pH of buffer solution containing 0.01 M CH₃COOH and 0.1 M CH3COONa,pKa = 4.75.
  (g) ThepK_a of CH₃COOH and pK_b of NH₄ OH are 4.76 and 4.75 respectively. Calculate pH of CH₃COONH₄ solution. (PK_w = 14)

Class 11th Chemistry - Thermodynamics Case Study Questions and Answers 2022 - 2023 - by Study Materials - Sep 09, 2022 - View & Read

• 1)

  Thermodynamics involve energy changes in chemical reactions and other processes. Internal energy is total energy stored in a substance. We can specify absolute value of volume but not the absolute value of internal energy. We can measure only change in internal energy (\(\triangle\)U). Work done on the system is taken as positive and work done by the system is taken as negative. Heat (q) absorbed by the system is +ve and heat given out by system is negative. \(\triangle\)U = q + w according to first law of thermodynamics. \(\triangle\)H (enthalpy change) is measured at constant pressure, \(\triangle\)U is measured at constant volume. \(\triangle\)H, \(\triangle\)S (entropy change), \(\triangle\)G (free energy change) and temperature help to decide spontaneity of the process.
  (a) What is \(\triangle\)U in adiabatic process?
  (b) If 701 J of heat is absorbed by the system and 394 J of work is done by the system. What is value of\(\triangle\) U?
  (c) 2 litres of an ideal gas at a pressure of 10 atm expands isothermally into vacuum until its total volume is 10 litres. How much heat is absorbed and work done in the expansion?
  (d) For an equilibrium H₂ O(1) \(\rightleftharpoons\) H₂ O(g), What are sign of \(\triangle\)G, \(\triangle\)H and \(\triangle\)S?
  (e) For N₂ O₄ (g) \(\rightleftharpoons\) 2NO₂ (g).
  (f) What is C_p- C_v equal to?
  (g) State second law of thermodynamics.

• 2)

  Observe the table of standard enthalpy change for fusion and vapourisation of some substances. Study the table and answer the following questions.
  Standard Enthalpy Changes of Fusion and Vapourisation

  Substance	Tf/K	\(\Delta_{f u s} \mathbf{H}^{\odot} /\left(\mathbf{k} \mathbf{J} \mathbf{m o l}^{-1}\right)\)	Tb/K	\(\Delta_{v a p} \mathbf{H}^{\odot} /\left(\mathbf{k} \mathbf{J} \mathbf{m o l}^{-1}\right)\)
  N2	63.15	0.72	77.35	5.59
  NH3	195.40	5.65	239.73	23.35
  HCl	159.0	1.992	188.0	16.15
  CO	68.0	6.836	82.0	6.04
  CH3COCH3	177.8	5.72	329.4	29.1
  CCl4	250.16	2.5	349.69	30.0
  H2O	273.15	6.01	373.15	40.79
  NaCI	1081.0	28.8	1665.0	170.0
  C6H6	278.65	9.83	353.25	30.8

  (a) Why is \(\triangle\)H_vap of NaCI highest?
  (b) What is \(\triangle\)s for H₂O(s) \(\rightarrow\) H₂O(I)?
  (c) Which has stronger intermolecular forces, CCl₄ or Acetone?
  (d) calculate \(\triangle\)U_vap for H₂O if \(\triangle\)H_vap = 40.66 kJ mol^-1 at 373 K for 1 mole.
  (e) NH₃(g) \(\rightarrow\) NH₃ (l). What is sign of \(\triangle\)s?
  (f) How is enthalpy of sublimation calculated?
  (g) What is relationship between ionisation enthalpy and ionisation energy?

• 3)

  We can measure the transfer of heat from one system to another which cause change in temperature. The magnitude of change in temperature depends upon heat capacity of the substance. The enthalpy change of reaction remains the same irrespective of number ofsteps is Hess's law.It helps to calculate enthalpy of formation, combustion and other enthalpy changes. Enthalpy change can also be calculated by using bond enthalpies. First law gives law of conservation of energy but does not give direction of reaction. Second law states, entropy of universe is continuously increasing due to spontaneous processes taking place in it. \(\Delta\)H and \(\Delta\)S (entropy change) cannot decide spontaneity of process. We need \(\Delta\)G (free energy change) which is -ve for spontaneous, +ve for non-spontaneous. \(\Delta\)G = 0 for process in equilibrium. \(\Delta\)G is related to equilibrium constant. If \(\Delta\)G = -ve, 'K' is +ve and vice versa. Third law of thermodynamics states the entropy of perfectly crystalline substance is zero at zero kelvin.
  (a) We can determine \(\Delta\)H _lattice with the help of cycle. Name the cycle.
  (b) How can we calculate enthalpy of solution?
  (c) What is molar heat capacity of water in equilibrium with ice at constant pressure?
  (d) \(\Delta \mathbf{H}_{f}^{\circ}\) of O₃, CaO, H₃ and HI are +142.2,- 643.9,-46, +25.95 kJ mol^-1. Arrange these in increasing order of stability.
  (e) Standard entropy of X₂ , Y₂ and XY₃ are 60, 40 and 50 JK^-1 mol^-1 respectively. For the reaction \(\frac{1}{2} \mathbf{X}_{2}+\frac{3}{2} \mathbf{Y}_{2} \longrightarrow \mathbf{X Y}_{3}, \Delta \mathbf{H}=-\mathbf{3 0}\) KJ to be at what temperature, process will be at equilibrium.
  (f) What are sign of \(\Delta\)H and \(\Delta\)S for process to be always spontaneous?
  (g) Give mathematical expression for second law of thermodynamics.

Class 11th Chemistry - State of Matter Case Study Questions and Answers 2022 - 2023 - by Study Materials - Sep 09, 2022 - View & Read

• 1)

  The pressure exerted by vapours over the liquid is called vapour pressure of liquid in a closed container. When liquid and vapour phase are in equilibrium, the vapour pressure of this stage is known as equilibrium vapour pressure or saturated vapour pressure. Vapour pressure depends upon temperature. Boiling point is temperature at which vapour pressure of liquid becomes equal to atmospheric pressure.
  (a) Why does water boil below 100°C at hill stations?
  (b) Why does vapour pressure of sea water is lower than distilled water?
  (c) Two liqurds 'X' and 'V' boil at 110°Cand 130°C respectively. Which of them has higher vapour pressure at 50°C?
  (d) What is boiling point of water inside the pressure cooker?
  (e) How is vapour pressure related to temperature?

• 2)

  Table shows critical temperatures of some substances. Study the table and answer the questions that follow:
  Critical Constants for Some Substances

  Substance	Tc/K	pc/bar	Vc /dm3mol -1
  H2	33.2	12.97	0.0650
  He	5.3	2.29	0.0577
  N2	126.0	33.9	0.0900
  O2	154.3	50.4	0.0744
  CO2	304.10	73.9	0.0956
  H2O	647.7	220.6	0.0450
  NH3	405.5	113.0	0.0723

  (a) Why is Helium most difficult to liquefy?
  (b) Out of CO₂ and NH₃ which will liquefy first?
  (c) Critical temperature of CH₄ and CO₂ are -81.9°C and 31.1°C respectively. Which of these have stronger intermolecular forces of attraction?
  (d) What is critical temperature?
  (e) What is critical volume? How is it related to 'b' van der Waals' constant?

• 3)

  Observe the graph A, B and C and answer the questions that follow based on the graph and related studied concepts.
  
  (a) Which law is depicted by graph A?
  (b) Give relationship between T₁,T₂ and T₃ .
  (c) Which law is depicted by graph B?
  (d) Give mathematical formula of Charle's law
  (e) Why are straight lines in graph C called isochore?
  (f) What is relationship between V₁, V₂, V₃ and V₄ ?
  (g) What is mathematical formula for Gay Lussac's law.

• 4)

  In ionic compounds, there is electrostatic forces between oppositely charged ions. Covalent bonds are present in polar as well as non-polar molecules. Polar molecules have dipole-dipole attraction. Polar molecules with non-polar molecules have dipole-induced dipole attraction, non-polar molecules have induced dipole-induced dipole, dispersion forces (London forces). H-bonds are present in some polar molecules. Ion-dipole attraction exist between ions and polar molecules intermolecular forces are negligible in gaseous state with large intermolecular space. Interdependence of some observable properties pressure, volume, temperature and mass lead to different gas laws, Boyle's law, Charle's law, Gay-Lussac's law, Avogadro's law and Dalton's law of partial pressure. Ideal gas equation pV = nRT is followed by ideal gases. At high pressure and low temerature intermolecular forces start operatin~ strongly and molecules come close to each other. They show positive and negative deviation from ideal gas behaviour and follow van der Waals' equation. Gases can be liquefied at low temperature and high pressure. Liquids have more intermolecular forces of attraction. Some properties of liquids, e.g., surface tension and viscosity are due to strong attractive forces.
  Molecules of gases are in constant random motion. Their velocity can be expressed as average velocity, root mean square velocity and most portable velocity.
  (a) Under what conditions real gases show ideal gas behaviour?
  (b) What type of forces of attraction exist between NO₃^- and water?
  (c) How are different types of velocities related to molar mass?
  (d) A gas at 350 K and 15 bar has molar volume 20% less than that for an ideal gas under the same conditions. What is value of 'Z'?
  (e) Why is HF liquid, HCI, HBr, HI are gases?
  (f) How is pressure of dry gas calculated?
  (g) What is Boyle's temperature?

Class 11th Chemistry - Chemical Bonding and Molecular Structure Case Study Questions and Answers 2022 - 2023 - by Study Materials - Sep 09, 2022 - View & Read

• 1)

  The attractive force which holds the two atoms together is called chemical bond. Covalent bond is formed by equal sharing of electrons. Coordinate bond is formed by unequal sharing of electrons. Ionic bond is formed by transfer of electrons from one atom to another. Octet rule, although very useful but it is not universally applicable. According to valence bond theory, covalent bond is formed by overlapping of half filled atomic orbitals resulting in lowering of energy and more stability. Bond order is the number of bonds between atoms in a molecule. Higher the bond order, more will be stability and bond dissociation enthalpy but smaller bond length. Polarity of covalent bond depends upon difference in electronegativity. Covalent character of bond depends upon polarising power, smaller cation and bigger anions have higher polarising power. VSEPR theory helps to predict shapes of molecules.
  (a) Write the, electron dot structure of N₂O.
  (b) What are ions present in CsI₃?
  (c) Out of CN⁺, CN^-, NO, which has highest bond order?
  (d) What is correct order of repulsion bp - bp, lp - lp and lp - bp?
  (e) Draw the structure of XeOF₄ on the basis of VSEPR theory.
  (f) Which out of B₂ ,CO, \(\mathrm{O}_{2}^{2-}\) and NO⁺ are paramagnetic and why?

• 2)

  An ionic compound has 3-D crystal lattice in which positive and negative charges are equal. The crystal lattice is stabilised by enthalpy of lattice formation, bond length, bond angle, bond enthalpy, bond order and bond polarity have significant effect on properties of compounds. All the properties of certain compounds cannot be explained by single structure, more than one structure of a compound to explain its property are called resonating structures.
  Dipole moment depends upon polarity and shapes of molecules. Shapes of molecules can be determined by VSEPR theory as well as hybridisation sp, Sp², Sp^3, Sp³d, Sp³ d² are linear, trigonal planar, tetrahedral, trigonal bipyramidal and octahedral geometery respectively. Hydrogen bond is formed between hydrogen and F, O, N. Intra-molecular H-bonding is within the molecules which is weaker than inter molecular H-bonding, between the molecules.
  (a) Why does CO₂ have zero dipole moment?
  (b) What is hybridisation of 'S' in SF₆ and its shape?
  (c) Why do all bonds in \(\mathrm{CO}_{3}^{2-}\) have equal bond length?
  (d) Why is o-nitropbenol steam volatile, p-nitropbenol is not?
  (e) Wby is bond angle in H₂ O is more tban H₂ S?
  (f) Why is  bond \(\sigma\) stronger than \(\pi\)-bond?
  (g) Arrange NaCl, NaBr, NaF. NaI in increasing order of ionic character.

• 3)

  Table shows the molecular orbital occupancy and molecular properties for B₂, C₂, N₂, O₂, F₂, and Ne₂. Observe this figure and answer the questions based on this diagram and related studied concepts.
  MO occupancy and molecular properties for B₂ through Ne₂.
  
  (a) Why does bond enthalpy of N₂ is higher than O₂?
  (b) Why is Ne₂ not formed according to M.O. theory?
  (c) Why F₂ diamagnetic where as O₂ paramagnetic?
  (d) Arrange B₂, C₂, N₂, O₂, F₂ in increasing order of stability. Give reason.
  (e) Why is F₂ more reactive than O₂ ?
  (f) Arrange B₂, C₂, N₂, O₂, F₂ in increasing order of bond length.
  (g) What is speciality of double bond in C₂?
  (h) How are C₂ and Li₂ molecules detected?

Class 11th Chemistry - Classification of Elements and Periodicity in Properties Case Study Questions and Answers 2022 - 2023 - by Study Materials - Sep 09, 2022 - View & Read

• 1)

  Modern periodic table arranges the elements in the increasing order of atomic number. It has 18 groups and 7 periods. Atomic numbers are consecutive in a period and increases in group in a pattern. Elements are divided into four blocks, s-block,p-block, d-block andf-block based on their electronic configuration. 78% of elements are metals, about 20 elements are non-metals and few elements like B, Si, Ge, As are metalloids. Metallic character increases down the group but decreases along the period from left to right. The physical and chemical properties vary periodically with their atomic numbers.
  Periodic trends are observed in atomic size, ionisation enthalpies, electron gain enthalpies, electronegativity and valence. Oxides of metals are basic, some are amphoteric. Non-metals form acidic oxides, some form neutral oxides. s-block elements are soft, highly reactive, do not show variable oxidation states. p-block elements are metals, non-metals as well as metalloids, show variable oxidation states, exist as solids, liquids and gases. d-block elements are metals, form coloured ions, show variable oxidation states, have high melting and boiling points. Lanthanoids and actinoids are f-block elements, form coloured ions. All actinoids are radioactive.
  (a) Name the elements which belong to d-block but are not transition metals.
  (b) What are representative elements?
  (c) What is difference between oxidation states of p-block and d-block elements?
  (d) Which group elements are most electropositive and why?
  (e) What happens to reactivity down the group 17?
  (f) What type of compounds are formed by element belonging to group 14 and third period? Identify the element.
  (g) What is formula of compound formed between AI and S

• 2)

  The atomic and ionic radii decrease with increase in atomic number along a period from left to right. Atomic size and ionic size increases down the group.
  Ionisation enthalpy decreases down the group and increases along a period from left to right. It also depends upon shielding effect as well as stability of electronic configuration.
  Electronegativity decreases down the group but increases along the period.
  (a) Arrange the elements of second period in increasing order of first ionisation enthalpy.
  (b) Arrange the elements of group 13 in increasing order of atomic size.
  (c) Select the' amphoteric oxides among the following:
  NO, B₂O₃, Cr ₂O₃, BeO, ZnO, CO₂ , Al₂ O₃
  (d) For an element I.E₁ = 738 kJ mol^-1, IE₂ = 1450 kJ mol^-1, IE₃ = 7700 kJ mol^-1, IE₄ = 1.1 x 10 ⁴ kJ mol^-1. Name the main group to which element belong. Why?

• 3)

  Observe the group shown in figure and answer the questions that follow based on the graph and related studied concepts.
  
  (a) Which group elements have lowest ionisation enthalpy and why?
  (b) Which group element have highest ionisation enthalpy and why?
  (c) Why is ionisation enthalpy of Be more than B?
  (d) Why does 'N' have higher ionisation enthalpy than O?

• 4)

  Study the table of electron gain enthalpies of some main group elements and answer the questions that follow based on table and related concepts.

  Group 1	\(\Delta_{\mathrm{eg}} \mathbf{H}\)	Group 16	\(\Delta_{\mathrm{eg}} \mathbf{H}\)	Group 17	\(\Delta_{\mathrm{eg}} \mathbf{H}\)	Group 0	\(\Delta_{\mathrm{eg}} \mathbf{H}\)
  H	-73					He	+48
  Li	-60	O	-141	F	-328	Ne	+116
  Na	-53	S	-200	CI	-349	Ar	+96
  K	-48	Se	-195	Br	-325	Kr	+96
  Rb	-47	Te	-190	I	-295	Xe	+77
  Cs'	-46	Po	-175	At	-270	Rn	+68

  (a) Why do group 1 elements have low electron gain enthalpies?
  (b) Why is electron gain enthalpy of sulphur more than oxygen?
  (c) Why do noble gases have +ve electron gain enthalpies?
  (d) Arrange P, S, CI, F is increasing order of electron gain enthalpeis.

• 5)

  Study the table 1 and 2 related to electronegativity values along the period 2 and 3 Group 1 and 17 and answer the questions that follow based on these.
  Electronegativity Values (on Pauling scale) Across the Periods

  Atom (Period II)	Li	Be	B	C	N	O	F
  Electronegativity	1.0	1.5	2.0	2.5	3.0	3.5	3.0
  Atom (period III)	Na	Mg	AI	Si	P	S	Cl
  Electronegativity	0.9	1.2	1.5	1.8	2.1	2.5	3.0

  Electronegativity Values (on Pauling scale) Down a Family

  Atom (Group I)	Electronegativity Value	Atom (Group XVII)	Eledronegativity Value
  Li	1.0	F	4.0
  Na	0.9	CI	3.0
  K	0.8	Br	2.8
  Rb	0.8	I	2.5
  Cs	0.7	At	2.2

  (a) How does electronegativity varies along a period and why?
  (b) Why does K and Rb have same electronegativity although Rb is bigger than K?
  (c) Why does electronegativity decrease down the group?
  (d) Why is CsF most ionic?
  (e) Why is H- ion bigger than F^- ion?
  (f) Why is Lil covalent?
  (g) Why is CI₂ O₇ more acidic than Cl₂O₅?

Class 11th Chemistry - Structure of Atom Case Study Questions and Answers 2022 - 2023 - by Study Materials - Sep 09, 2022 - View & Read

• 1)

  Orbitals are region or space wher.e there is maximum probability of finding electrons. Qualitatively, these orbitals can be distinguished by their size, shape and orientation. An orbital of small size means there is more chance of finding the electron near the nucleus. Shape and orientation means the direction in which probability of finding electron is maximum. Atomic orbitals can be distinguished by quantum numbers. Each orbital is designated by three quantum numbers n, I and m₁ (magnetic quantum number) which define energy, shape and orientation but these are not sufficient to explain spectra of multi-electrons atoms. Spin quantum number (m_s ) determines the spin of electron. Spin angular momentum of electron has two orientations relative to chosen axis which are distinguished by spin quantum numbers m_s which can take values +1/2 and -1/2.

  Value of 'l'	0	1	2	3	4
  Notation for subshell	s	p	d	f	g

  (a) How many orbitals are associated with n = 3?
  (b) Describe the orbitals represented by (i) n = 2, l = 1 (ii) n = 4, l = 0.
  (c) How many electron are possible in an orbital? Why?
  (d) What is shape of 's' and 'p' orbitals?
  (e) Name two d-orbitals which are on axis.

• 2)

  The plots of (a) orbital wave function \(\Psi\)(r) and (b) the variation of probability density\(\Psi\) ²(r) as function of distance'r' of the electron from the nucleus for Is and 2s orbitals are shown in the figure. Answer the questions as follows based on graph and related studied concepts.
  
  
  (a) What is meant by\(\Psi\)?
  (b) What is meant by \(\Psi\)²?
  (c) What happens to probability density in Is orbital?
  (d) What happens to \(\Psi\) ² in '2s' orbital?
  (e) What are nodes?
  (f) How many nodes are 1s, 2s, 3s orbitals?
  (g) What are angular nodes?
  (h) How many radial and angular nodes are there in 3d orbital?

• 3)

  Bohr's model explained electrons can revolve only in certain permitted orbits whose angular momentum is integral multiple of h/2\(\pi\), associated with fixed amount of energy. Bohr theory could successfully explain stability of atoms and spectrum of unielectron species. Hydrogen spectrum consist of Lyman, Balmer, Paschen, Brackett and Pfund series. Bohr's theory could not explain spectrum of multi-electron species, Stark effect, Zeeman effect, dual nature of matter, de Broglie equation and Heisenberg uncertainty principle which lead to orbital concept. Electrons were filled in orbitals according to Autbau's principle, Hund's Rule and Pauli's exclusion principle. Each electron is identified by four quantum numbers n, I, m_l and m_s out which n, I, m_l were derived from Schrodinger's wave equation. Half filled and completely filled orbitals are more stable due to exchange energy and symmetrical distribution of electrons.
  (a) Heat treatment of muscular pain involves radiation of wavelength 900 nm which spectral line of H-atom is suitable for this purpose.
  (b) Arrange 4d, 3d, 4p and 3p in increasing order of energy.
  (c) What is name of spectrum of radiation emitted by substance that has absorbed radiation?
  (d) What rules out the probability of existence of definite path of electrons?
  (e) State de Broglie equation.
  (f) The angular momentum of d-orbital is equal to?
  (g) State Pauli exclusion principle.

Class 11th Chemistry - Some Basic Concept of Chemistry Case Study Questions and Answers 2022 - 2023 - by Study Materials - Sep 09, 2022 - View & Read

• 1)

  Stoichiometry is a section of chemistry that involves calculation based on chemical equations. Chemical equations are governed by laws of chemical combination. Mass of reactants is equal to mass of products. Compound obtained from different methods contain the same elements in the fixed ratio by mass. Mole is a counting unit, equal to 6.022 x 10²³ particles.
  One mole is also equal to molar mass expressed in grams. One mole of every gas at STP has volume equal to 22.4 L. The reacting species which are consumed in the reaction completely is called limiting reagent which decides amount of products formed. Concentration of solution is expressed in terms of molarity, molality and mole fraction.
  (a) Calculate number of moles of NH₃ formed by reaction of 2 moles of N₂ and 2 moles of H₂.
  \(\mathbf{N}_{2}(g)+3 \mathbf{H}_{2}(g) \longrightarrow 2 \mathrm{NH}_{3}(g)\)
  (b) Calculate number of electrons in 18 g of H₂ O. [Atomic number of H = 1 ,O = 8]
  (c) Calculate the molality of 1 M NaCI solution having density 1.10 g cm^-3. (Molar mass = 58.5 g mol^-1)
  (d) Define mole fraction.
  (e) In aqueous solution of glucose X_glucose = 0.1, what is X_H2O = ?

• 2)

  In the table given below to illustrate precision and accuracy. Study the table and answer the questions based on the table and related studied concepts.
  Data to Illustrate Precision and Accuracy

  Measurement in g	I	II	III	Average
  student A	0.521 g	0.515 g	0.509 g	0.515 g
  student B	0.516 g	0.515 g	0.514 g	0.515 g
  student C	0.521 g	0.520 g	0.520 g	0.520 g

  (a) What is meant by precision?
  (b) What is accuracy?
  (c) If actual mass of a piece of metal is 0.520 g, data for which student is neither precise nor accurate.
  (d) Which student data is precise but not accurate?
  (e) The data of which student is both precise and accurate?
  (f) How many significant figures are in 0.520?
  (g) What is scientific notation for 0.520?

• 3)

  Chemistry play an important role in human needs for food, health care products and improving life. Cis platin and taxol are used in chemotherapy, AZT (Azidothymidine) is used for AIDS. SI units are international units of measurement. Matter is classified into elements, compounds and mixtures, which can be homogeneous as well as heterogeneous. A mixture can be separated by physical methods, compounds can be separated by chemical methods only. Atomic mass is average of masses of isotopes depending upon their natural abundance. Empirical formula is calculated with the help of percentage composition of elements in a compound and molecular mass helps to calculate molecular formula. A chemical equation must be balanced so as to follow laws of chemical combination.
  (a) Express 2.54 mm into S.I units.
  (b) Out of milk, diamond, air, petrol which is pure substance?
  (c) Balance the equation: NO₂ + H₂ O \(\rightarrow\) HNO₃ + NO
  (d) What is percentage of Na in Na₂CO₃ ? (Na = 23u, C = 12, O = 16u)
  (e) \({ }_{17}^{35} \mathrm{Cl} \text { and }{ }_{17}^{37} \mathrm{Cl}\) are in ratio of 3 : 1 in nature. What is atomic mass of CI?
  (f) What is empirical formula of C₆H₁₂O₆?
  (g) Chlorophyll contains 2.68% magnesium atoms. Calculate mass of magnesium atoms in 2 g of chlorophyll.

11th Standard CBSE Mathematics Public Exam Model Question 2020 - by Ashutosh Saran - Gurgaon - Mar 03, 2020 - View & Read

• 1)

  One mole of CO₂ contains _______.

• 2)

  de Broglie equation is _______.

• 3)

  The highest ionization energy is exhibited by _____.

• 4)

  The axial overlap between the two orbitals leads to the formation of a: ______.

• 5)

  Which of the following is the correct mathematical relation for Charles law at constant pressure?

11th Standard CBSE Chemistry Public Exam Sample Question 2020 - by Ashutosh Saran - Gurgaon - Mar 03, 2020 - View & Read

• 1)

  How many grams are contained in 1 gram atom of Na?

• 2)

  The orbital with n = 3 and 1 = 2 is _______.

• 3)

  What is the electronic configuration of the elements of group 14?

• 4)

  Which one is diamagnetic among NO⁺ , NO and NO^-?

• 5)

  At constant temperature, the pressure of the gas is reduced to one-third, the volume

11th Standard CBSE Chemistry Public Exam Important Question 2019-2020 - by Ashutosh Saran - Gurgaon - Mar 03, 2020 - View & Read

• 1)

  The mass of an atom of nitrogen is _______.

• 2)

  In a sodium atom (atomic number = 11 and mass number = 23) and the number of neutrons is _______.

• 3)

  In halogens, which of the following, increases from iodine to fluorine?

• 4)

  The species CO, CN^- and N₂ are ______.

• 5)

  Viscosity of a liquid is a measure of

11th Standard Chemistry Board Exam Sample Question 2020 - by Ashutosh Saran - Gurgaon - Mar 03, 2020 - View & Read

• 1)

  The empirical formula of sucrose is _______.

• 2)

  Cathode rays are deflected by _______.

• 3)

  Which of the following is arranged in order of increasing radius?

• 4)

  The molecule Ne₂ does not exist because ______.

• 5)

  With rise in temperature, the surface tension of a liquid

11th Standard Chemistry Board Exam Model Question 2019-2020 - by Ashutosh Saran - Gurgaon - Mar 03, 2020 - View & Read

• 1)

  12 g of Mg will react completely with an acid to give: _______.

• 2)

  The energy needed to remove a single electron (most loosely bound) from an isolated gaseous atom is called _______.

• 3)

  In halogens, which of the following, increases from iodine to fluorine?

• 4)

  Out of the following, intramolecular hydrogen bonding exists in ______.

• 5)

  The cleansing action of soaps and detergents is due to

CBSE 11th Chemistry - Public Model Question Paper - by Ashutosh Saran - Gurgaon - Jan 18, 2020 - View & Read

• 1)

  3 L water is added to 2 L of 5 M HCl. What is the molarity of HCl in the resultant solution?

• 2)

  Air contains about 99% of N₂ and O₂ gases. Why do not they combine to form NO under the standard conditions? Standard Gibbs energy of formation of NO (g) is 86.7 kJ mol^-1.

• 3)

  what is the nature of 'photochemical smog'?

• 4)

  What is the significance of wave function \(\Psi \) in the Schrodinger wave equation?
  What is an atomic orbital? Why \(\Psi \) is called orbital wave function?

CBSE 11th Chemistry - Some Basic Concept of Chemistry Model Question Paper - by Ashutosh Saran - Gurgaon - Nov 20, 2019 - View & Read

• 1)

  One mole of CO₂ contains _______.

• 2)

  5.6 litres of oxygen at NTP is equivalent to _______.

• 3)

  12 g of Mg will react completely with an acid to give: _______.

• 4)

  The number of significant figures in 0.0101 is _______.

• 5)

  The mass of an atom of nitrogen is _______.

CBSE 11th Chemistry - Full Syllabus One Mark Question Paper with Answer Key - by Ashutosh Saran - Gurgaon - Nov 04, 2019 - View & Read

• 1)

  One mole of CO₂ contains _______.

• 2)

  5.6 litres of oxygen at NTP is equivalent to _______.

• 3)

  Which of the following has the highest mass?

• 4)

  The number of significant figures in 0.0101 is _______.

• 5)

  The mass of an atom of nitrogen is _______.

CBSE 11th Chemistry - Full Syllabus Five Marks Questions - by Ashutosh Saran - Gurgaon - Nov 01, 2019 - View & Read

• 1)

  How many atoms of He are present in 52 \(\mu\) of He?

• 2)

  Insulin contains 4.5 % sulphur. Calculate the minimum molecular mass of sulphur.

• 3)

  Calcium carbonate reacts with aqueous HCI to give CaCL₂ and CO₂ according to the reaction given below CaCO₃(s) + 2HCI(aq) \(\longrightarrow \)CaCl₂(aq) + CO₂(g) + H₂O(l)
  What mass of CaCl₂ will be formed when 250 mL of 0.76 M HCI reacts with 1000 g of CaCO₃? Name the limiting reagent. Calculate the number of moles of CaCL₂ formed in the reaction.

CBSE 11th Chemistry - Full Syllabus Four Marks Questions - by Ashutosh Saran - Gurgaon - Nov 01, 2019 - View & Read

• 1)

  Convert the following into basic units. 15.5 \(\mu s\)

• 2)

  Calculate
  (5.7 x 10^-5) \(\div \) (4.2 x 10^-3)

• 3)

  The density of 3 M solution of Na Cl is 1.25 g mL^-1. Calculate molality of the solution.

• 4)

  Assuming the density of water  to be 1g/cm³, calculate the volume occupied by one molecule of water.

• 5)

  50.0 kg of \({ N }_{ 2 }(g)\) and 10.0 kg of \({ H }_{ 2 }(g)\) are mixed to produce \(NH_{ 3 }(g)\)formed. Identify the limiting reagent in the productuion of \(NH_{ 3 }\) in this situation.

CBSE 11th Chemistry - Full Syllabus Three Marks Questions - by Ashutosh Saran - Gurgaon - Nov 01, 2019 - View & Read

• 1)

  Write the complete symbol for the atom with the given number (Z) and atomic mass (A).
  (a) Z = 92, A = 233
  (b)  Z = 4, A = 9

• 2)

  With what 7'elocity must an electron travel so that its momentum is equal to that of a photon of wavelength = 5200 \(\mathring { A } \) ?

• 3)

  What do you understand by isoelectronic species? Name a species that will be isoelectronic with the following atom or ion. Ar

CBSE 11th Chemistry - Full Syllabus Two Marks Questions - by Ashutosh Saran - Gurgaon - Nov 01, 2019 - View & Read

• 1)

  Convert the following into kg.
  (a) "0.91 x 10^-27 g( mass of electron)"
  (b) "700g (mass of human DNA molecule )"

• 2)

  If the concentration of glugose (C₆H₁₂O₆) in blood is 0.9 g L^-1, what will be the molarity of glugose blood?

• 3)

  Express the following in SI unit. "5 feet 2 inch"

• 4)

  How many oxygen atoms are there in 18 g of water?

• 5)

  What would be IUPAC names and symbols for elements with atomic numbers 122,127,135,149 and 150?

CBSE 11th Standard Chemistry - The p-block Elements Five Marks Model Question Paper - by Amit Pandya - Varanasi - Oct 11, 2019 - View & Read

• 1)

  What are the allotropes? Sketch the structure of two allotropes of carbon namely diamond and graphite.What is the impact of structure on physical properties of two allotropes?

• 2)

  What happens when borax is heated strongly?

• 3)

  Complete the following reactions
  \(CO+{ H }_{ 2 }\xrightarrow [ ZnO,{ Cr }_{ 2 }{ O }_{ 3 } ]{ 200 \ atm, \ 675K } \)

• 4)

  Complete the following reactions
  \({ CaCO }_{ 3 }(aq)+{ CO }_{ 2 }(excess)\longrightarrow \)

• 5)

  What happens when aluminium is treated with dilute NaOH?

CBSE 11th Standard Chemistry - Organic Chemistry: Some Basic Principles and Techniques Five Marks Model Question Paper - by Amit Pandya - Varanasi - Oct 11, 2019 - View & Read

• 1)

  An organic compound contains 69% carbon and 4.8% hydrogen, the remainder being oxygen. Calculate the masses of carbon dioxide and water produced when 0.20 g of this substance is subjected to complete combustion.

• 2)

  Explain why \({ \left( { CH }_{ 3 } \right) }_{ 3 }\overset { + }{ C } \) is more stable than \({ CH }_{ 3 }\overset { + }{ C } { H }_{ 2 }\) and \(\overset { + }{ C } { H }_{ 3 }\)is the least stable cation.

• 3)

  Give condensed and bond line structural formulas and identify the functional group(s) present, if any, for :
  (a) 2,2,4-Trimethylpentane
  (b) 2-Hydroxy-1,2,3-propanetricarboxylic acid
  (c) Hexanedial

• 4)

  Explain the terms inductive and electromeric effects. Which electron displacement effect explain the following correct orders of acidity of the carboxylic acids?
  (a) Cl₃CCOOH > Cl₂CHCOOH > ClCH₂COOH
  (b) CH₃CH₂COOH > (CH₃)₂CHCOOH > (CH₃)₃C.COOH

11th Standard CBSE Chemistry - Hydrocarbons Five Marks Model Question Paper - by Amit Pandya - Varanasi - Oct 11, 2019 - View & Read

• 1)

  Arrange the following set of compounds in order of their decreasing relative reactivity with an electrophile, E+.
  (i) Chlorobenzene, 2, 4-dinitrochlorobenzene, p-nitrochlorobenzene
  (ii) Toluene,  \(p-{ H }_{ 3 }C-{ C }_{ 6 }{ H }_{ 4 }-{ NO }_{ 2 },\)
  \(p-{ O }_{ 2 }N-{ C }_{ 6 }{ H }_{ 4 }-{ NO }_{ 2 }\)
  Also explain ur answer.

• 2)

  Write IUPAC names of the products obtained by the ozonolysis of the following compounds :
  (i) Pent-2-ene
  (ii) 3,4-Dimethylhept-3-ene
  (iii) 2-Ethylbut-1-ene
  (iv) 1-Phenylbut-1-ene

• 3)

  How will you convert benzene into
  (i) p-nitrobromobenzene
  (ii) m- nitrochlorobenzene
  (iii) p - nitrotoluene
  (iv) acetophenone?

• 4)

  Addition of HBr to propene yields 2-bromopropane, while in the presence of benzoyl peroxide, the same reaction yields 1-bromopropane. Explain and give mechanism.

• 5)

  How would you convert the following compounds into benzene?
  (i) Ethyne
  (ii) Ethene
  (iii) Hexane

11th Standard CBSE Chemistry - Environmental Chemistry Five Marks Model Question Paper - by Amit Pandya - Varanasi - Oct 11, 2019 - View & Read

• 1)

  What is 'Acid Rain'? How is it harmful to the environment?

• 2)

  What is photochemical smog? What are its effects? How can it be controlled?

• 3)

  (a) Define eutrophication and pneumoconiosis.
  (b) Write difference between photochemical and classical smog.

• 4)

  Have you ever observed any water pollution in your area? What measures would you suggest to control it?

• 5)

  Do you observe any soil pollution in your neighbourhood? What efforts will you make for controlling the soil pollution?

CBSE 11th Chemistry - Environmental Chemistry Four and Five Marks Questions - by Ashutosh Saran - Gurgaon - Oct 09, 2019 - View & Read

• 1)

  How is the temperature effected as we go up the earth's surface? Explain

• 2)

  It is advised not to sleep in a closed room with burning coke angithi to warm up. Explain.

• 3)

  Sonu and Nilesh were friends. In winters, one day when they were going to school at 10:00 am Sonu felt irritation in his eyes and throat. He was also unable to breath.
  Nilesh immediately took him to a doctor. Doctor gave him the proper remdy. When he became well, Nilesh asked reason for this Doctor answered him satisfactorily.
  (i) Can you guess what reason was given by the doctor for the illness of Sonu.
  (ii) Why such kind of polluting atmospheric change occurs?
  (iii) What should be done to prevent the formation of smog?
  (iv) What values are possessed by Nilesh?

• 4)

  How carbon monoxide acts as a poison for human beings?

• 5)

  What is 'Acid Rain'? How is it harmful to the environment?

CBSE 11th Chemistry - Hydrocarbons Four and Five Marks Questions - by Ashutosh Saran - Gurgaon - Oct 09, 2019 - View & Read

• 1)

  Which of the following compounds will show cis-trans isomerism?
  (CH₃)₂C=CH-C₂H₅

• 2)

  Which of the following compounds will show cis-trans isomerism?
  CH₂= CBr₂

• 3)

  Write chemical equations for combustion reaction of the following hydrocarbons:
  (i) Butane
  (ii) Pentene
  (iii) Hexyne
  (iv) Toluene

• 4)

  Arrange the following set of compounds in order of their decreasing relative reactivity with an electrophile, E+.
  (i) Chlorobenzene, 2, 4-dinitrochlorobenzene, p-nitrochlorobenzene
  (ii) Toluene,  \(p-{ H }_{ 3 }C-{ C }_{ 6 }{ H }_{ 4 }-{ NO }_{ 2 },\)
  \(p-{ O }_{ 2 }N-{ C }_{ 6 }{ H }_{ 4 }-{ NO }_{ 2 }\)
  Also explain ur answer.

• 5)

  Write IUPAC names of the products obtained by the ozonolysis of the following compounds :
  (i) Pent-2-ene
  (ii) 3,4-Dimethylhept-3-ene
  (iii) 2-Ethylbut-1-ene
  (iv) 1-Phenylbut-1-ene

CBSE 11th Chemistry - Organic Chemistry: Some Basic Principles and Techniques Four and Five Marks Questions - by Ashutosh Saran - Gurgaon - Oct 09, 2019 - View & Read

• 1)

  An organic compound contains 69% carbon and 4.8% hydrogen, the remainder being oxygen. Calculate the masses of carbon dioxide and water produced when 0.20 g of this substance is subjected to complete combustion.

• 2)

  Explain why \({ \left( { CH }_{ 3 } \right) }_{ 3 }\overset { + }{ C } \) is more stable than \({ CH }_{ 3 }\overset { + }{ C } { H }_{ 2 }\) and \(\overset { + }{ C } { H }_{ 3 }\)is the least stable cation.

• 3)

  Sohan was very upset from last few days when he came to know that his father is alcoholic (takes alcohol).He knows about the side effects of the alcohol so want to keep away his father from it.He decided to talk about this with his father.When he asked his father about it, he told him, that he is not alcoholic, only occasionally he takes it but of Sohan does not even want him to ever touch it.
  (a) What is the main constituent of alcoholic beverages?
  (b) Write the IUPAC name and hybridization of this main constituent.
  (c) What are the side effects of alcoholic beverages?
  (d) What values are possessed by Sohan and his father?

CBSE 11th Chemistry - The p-block Elements Four and Five Marks Questions - by Ashutosh Saran - Gurgaon - Oct 09, 2019 - View & Read

• 1)

  Among group 14 elements name most metallic element

• 2)

  Among group 14 elements name  the elements having tendency to from \(p\pi -p\pi \) bonds.

• 3)

  Carbon form covalent compounds whereas lead form ionic compounds.why?

• 4)

  A colorless aqueous solution on adding water and on heating gave a white NH₄Cl and NH₄OH in excess resulted in the dissolution of some of the precipitate and a gelatinous precipitate is obtained.what is the hydroxide formed in aqueous solution?

• 5)

  Aluminium dissolves in mineral acids and aqueous alkalies and thus shows amphoteric character.A piece of aluminum foil is treated with dilute hydrochloric acid or dilute sodium hydroxide solution in a test tube and on bringing a burning matchstick near the mouth of the test tube, a pop sound indicates the evolution of hydrogen gas.The same activity when performed with concentrated nitric acid, reaction doesn't proceed, Explain the reason.

CBSE 11th Chemistry - The s-Block Elements Four and Five Marks Questions - by Ashutosh Saran - Gurgaon - Oct 09, 2019 - View & Read

• 1)

  Explain why ?
  The crystalline salts of alkaline earth metals contain more water of crystallisation than the corresponding alkali metal salts.

• 2)

  Dr.Sharma , cardiologist suggested his patienta to take more potassium ions for healthy heart. potassium ions are the most abundant cations within cell fluids, where they activate many enzymes, participate in the oxidation of glucose to pro duse ATP While sodiun ions are responsible for the transmission for nerve signals. It  intake of potassium , harmful for our body?

• 3)

  Dr.Sharma , cardiologist suggested his patienta to take more potassium ions for healthy heart. potassium ions are the most abundant cations within cell fluids, where they activate many enzymes, participate in the oxidation of glucose to pro duse ATP While sodiun ions are responsible for the transmission for nerve signals. What are the sources of potassium ?

• 4)

  Give the reson for following Potassium carbonate cannot be prepared by Solvay ammonia process.

• 5)

  Reema takes milk every day . She also take curd and other milk products.She takes green leafy vegitables and fruits also. An adult body contains about 25g of magnesium and 1200 g of calcium and 5 g of iron .these elements must be a part of our diet. All enzymes that utilize ATP in phosphate transfer required magnesium as co-factor. the main pigment for the absorption of light in plants is chlorophyll, which contains magnesium. were as Anita does not like milk and takes lot of junk food.

  Why should we take green leafy vegitables in our dite?

CBSE 11th Chemistry - Hydrogen Four and Five Marks Questions - by Ashutosh Saran - Gurgaon - Oct 09, 2019 - View & Read

• 1)

  An ionic hydride of an alkali metal has significant covalent character and is almost unreactive towards oxygen and chlorine. This is used in the synthesis of other useful hydrides. Write its reaction with \({ Al }_{ 2 }{ Cl }_{ 6 }\)

• 2)

  At the home of Mr.Kumar, Dalda ghee is generally used. He is suffering from high blood pressure and diabetes. Mr.Sharma, a friend of Mr.Kumar has advised him to change from ghee to vegetable oil like mustard oil.
  Dihydrogen (H₂) is used in the manufacture of vanaspati ghee by hydrogenation of polyunsaturated vegetable oils using nickel as a catalyst.
  Vegetable oil \(\xrightarrow [ { H }_{ 2 } ]{ Ni } \) vanaspati ghee
  Should we use vegetable oils for cooking? why?

• 3)

  In India, there is the shortage of drinking water. Thus, projects like rainwater harvesting are used by Green Park Association to increase the amount of underground water. Rainwater is the almost pure form of water after the heavy shower as it is, in fact, the distilled water. The first shower contains dissolved gases from the atmosphere. Being a good solvent, when it flows on the surface of the earth, it dissolves many salts in the form of hydrogen carbonate, chloride and sulphate in water which make it hard Give the values possessed by the office bearer of Green Park Association?

• 4)

  Scientist of UK has designed the cars, working on hydrogen fuel cells instead of petrol engines. Here hydrogen is used as sources of electrical energy i.e. a reaction of hydrogen and oxygen is used to generate electrical energy. It has many advantages over the conventional fossil fuels and electric power generation.
  Give two advantages of hydrogen over fossil fuels?

• 5)

  Scientist of UK has designed the cars, working on hydrogen fuel cells instead of petrol engines. Here hydrogen is used as sources of electrical energy i.e. a reaction of hydrogen and oxygen is used to generate electrical energy. It has many advantages over the conventional fossil fuels and electric power generation.
  What are the values possessed by scientists of UK?

CBSE 11th Chemistry - Redox Reactions Four and Five Marks Questions - by Ashutosh Saran - Gurgaon - Oct 09, 2019 - View & Read

• 1)

  Justify that the reactions
  4Na(s) + O₂(g) \(\rightarrow \) 2Na₂O(s) are redox reactions.

• 2)

  Given the standard electrode potentials, K⁺/K = -2.93V, Ag⁺/Ag = 0.80V, Hg²⁺/Hg = 0.79V, Mg²⁺ / Mg = -2.37V, Cr³⁺/Cr = -0.74V arrange these metals in their increasing order of reducing power.

• 3)

  Predict whether the following cell does exist or not?
  Zn|Zn²⁺(1M)||Cd²⁺(1M)|Cd
  Given,
  \(\left[ { E }_{ Zn,{ Zn }^{ 2+ } }^{ 0 }=0.76V \ and \ { E }_{ Cd,{ Cd }^{ 2+ } }^{ 0 }=0.40V \right] \)

• 4)

  Identify the redox reaction out of the following reactions and identify the oxidising and reducing in them.
  (i) 3HCl(aq) + HNO₃(aq) \(\longrightarrow \) Cl₂(g) +NOCl(g) + 2H₂O(l)
  (ii) \({ Hgcl }_{ 2 }(aq)+2KI(aq)\longrightarrow { HgI }_{ 2 }(s)+{ 2KCl(aq) }\)
  (iii) Fe₂O₃ (s) + 3CO(g) \(\overset { \Delta }{ \longrightarrow } \)2Fe(s) +3CO₂(g)
  (iv) PCl₃(l)+3H₂O(l)⟶3HCl(aq)+H₂PO₃(aq)
  (v) 4NH₃(aq) + 3O₂(g) \(\longrightarrow \) 2N₂(g) + 6H₂O(g)

11th Standard CBSE Chemistry - Equilibrium Four and Five Marks Questions - by Ashutosh Saran - Gurgaon - Oct 09, 2019 - View & Read

• 1)

  For the equilibrium, \(2NOCl\left( g \right) \rightleftharpoons 2NO\left( g \right) +{ Cl }_{ 2 }\left( g \right) \) the value of the equilibrium constant, K_c is 3.75 × 10^–6 at 1069 K. Calculate the K_p for the reaction at this temperature?

• 2)

  K₁ and K₂ for dissociation of H₂S are 4 x 10^-7 and 1 x 10^-5. Calculate sulphide ion concentration in 0.1M H₂S Solution.

11th Standard CBSE Chemistry - Chemical Bonding and Molecular Structure Four and Five Marks Questions - by Ashutosh Saran - Gurgaon - Oct 05, 2019 - View & Read

• 1)

  Give the geometry of (CH₃)₃N and [(CH₃)₃Si]₃N state if they are isostructural?

• 2)

  One day when Ravi was passing by his laboratory and felt some suffocating odour. He saw his laboratory attendant was preparing some chemical, named as ammonia. Suddenly, he saw that some chemical had fallen at the hand of the attendant. He run at once and take some highly diluted HCl and apply at the burned place.By this the attendent got relief.
  Can you predict and draw the structures of these compound.Also mark the central atom and find out the bond pairs and lone pairs.

• 3)

  Rahul, a brilliant science student, was very keen to do experiments and get knowledge from them. One day he took some sugar and salt separately and added some acid of sulfur (which is generally used for toilet cleaning) and notice the changes. He got confused as he expected that the reaction of salt should be faster. Next day he asked about his experiment to his science teacher, who clarity the reason for the result he got. He got satisfied.
  Draw the electron dot structure of acid of sulphur and salt.

• 4)

  Write the resonance structures for SO₃, NO₂ and NO^-₃

• 5)

  Explain with the help of suitable example polar covalent bond.

11th Standard CBSE Chemistry - State of Matter Four and Five Marks Questions - by Ashutosh Saran - Gurgaon - Oct 05, 2019 - View & Read

• 1)

  On a ship sailing in Pacific ocean where temperature is \(23.4^{ \circ }C\) , a balloon is filled with 2L air. What will be the volume of the balloon when the ship reaches Indian ocean, where temperature is  \(26.1^{ \circ }C\) ?

• 2)

  An iron cylinder contains helium at a pressure of 250 KPa at 300 K. The cylinder can withstand a pressure of \(1\times { 10 }^{ 6 }Pa\) . The room in which cylinder is placed catches fire. Predict whether the cylinder will blow up before it melts or not (mp of the cylinder = 1800 K).

• 3)

  Gases possess characteristic critical temperature which depends upon the magnitude of intermolecular forces between the gas particles. The critical temperature of ammonia and carbon dioxide are 405.5 K and 304.10 K respectively. Which of these gases will liquify first when you start cooling from 500 K to their critical temperature?

• 4)

  Rainy season brings lots of happiness as well as lots of diseases also.Malaria, dysentery, jaundice are common diseases that occurred in this season.Children usually get affected by these diseases.Renu's teacher advised the class to drink boiled water.She also explained to test jaundice by doing a simple test based on the property of surface tension.She told them to take the urine sample in a glass and sprinkle the sulphur powder over it.If it floats, the test is negative but if it sinks, it is positive.After reading the above paragraph, answer the following questions.
  What is the reason that sulphur powder floats if the test is negative but it sinks if it is positive?

• 5)

  Rainy season brings lots of happiness as well as lots of diseases also.Malaria, dysentery, jaundice are common diseases that occurred in this season.Children usually get affected by these diseases.Renu's teacher advised the class to drink boiled water.She also explained to test jaundice by doing a simple test based on the property of surface tension.She told them to take the urine sample in a glass and sprinkle the sulphur powder over it.If it floats, the test is negative but if it sinks, it is positive.After reading the above paragraph, answer the following questions.
  What values are expressed in the above paragraph.

11th Standard CBSE Chemistry - Thermodynamics Four and Five Marks Questions - by Ashutosh Saran - Gurgaon - Oct 05, 2019 - View & Read

• 1)

  Calculate \({ \triangle }G^{ \ominus }\)for the reaction
  4NH₃(g) + 5O₂(g)\(\longrightarrow \) 4NO(g) + 6H₂O(l)
  given that \({ \triangle }G^{ \ominus }\) for the formation of NH₃ (g), NO(g) AND H₂O (l) are - 16.8 KJ mol^-1 +86.7 KJ mol^-1 and -237.2KJ mol^-1 respectively. predict feaibility of reaction under the conditions.

• 2)

  Determine whether or not it is possible for sodium to reduce aluminium oxide to aluminium at 298 K.
  \(\triangle _{ f }G^{ \ominus } \ { Al }_{ 2 }{ O }_{ 3 }(s)=-1582 \ KJ \ { mol }^{ -1 };\triangle _{ f }G^{ \ominus }Na_{ 2 }O(s)=-377 \ KJ \ { mol }^{ -1 }\)

• 3)

  Calculate \(\triangle _{ r }G^{ \ominus }\) for conversion of oxygen to ozone, 3/2 O₂(g) \(\rightarrow \) O₃(g) at 298 K_p. If K_p for this conversion is 2.47 x 10^-29.

• 4)

  Define the following:
  (i) First law of thermodynamics.
  (ii) Standard enthalpy of formation

11th Standard CBSE Chemistry - The s-Block Elements Five Mark Model Question Paper - by Amit Pandya - Varanasi - Oct 04, 2019 - View & Read

• 1)

  Name the groups which constitute s-block elements.

• 2)

  Why is the density of potassium less than sodium ?

• 3)

  What happens when K burns in air ? Give chemical equation.

• 4)

  Starting with sodium chloride how would you proceed to prepare? sodium hydroxide.

• 5)

  Starting with sodium chloride how would you proceed to prepare? Sodium peroxide.

11th CBSE Chemistry - Hydrogen Five Mark Model Question Paper - by Amit Pandya - Varanasi - Oct 04, 2019 - View & Read

• 1)

  What do you expect the nature of hydrides is, if formed by elements of atomic numbers 15, 19, 23, 44 with dry dilhydrogen? Compare their behaviour towards water.

• 2)

  How would you prepare dihydrogen from a substance other than water?

• 3)

  What mass of hydrogen peroxide will be present in 2L of a 5M solution?

• 4)

  Calculate the mass of oxygen which will be liberated by the decomposition of 200mL of this solution.

• 5)

  Complete the following chemical reactions and classify the above into (a) hydrolysis,(b) redox and (c) hydration reactions.
  \(PbS(s)+{ 4 }H_{ 2 }{ O }_{ 2 }(aq)\rightarrow \)

CBSE 11th Standard Chemistry - Redox Reactions Five Mark Model Questions - by Amit Pandya - Varanasi - Oct 03, 2019 - View & Read

• 1)

  Justify that the following reaction are redox reaction
  (a) \(CuO(s)+{ H }_{ 2 }(g)\rightarrow Cu(s)+{ H }_{ 2 }O(g)\)
  (b) \({ F }e_{ 2 }O_{ 3 }(s)+3CO(g)\rightarrow 2Fe(s)+3{ CO }_{ 2 }(g)\)
  (c) \(4BCl_{ 3 }(g)+3LiAl{ H }_{ 4 }(s)\longrightarrow 2{ B }_{ 2 }{ H }_{ 6 }(g)+3LiCl(s)+3AlC{ l }_{ 3 }(s)\)
  (d) \(2k(s)+{ F }_{ 2 }(g)\longrightarrow 2K^{ + }{ F }^{ - }(s)\)
  (e) \(4N{ H }_{ 3 }(g)+5{ O }_{ 2 }(g)\longrightarrow 4NO(g)+6H_{ 2 }O(g)\)

• 2)

  Justify that the following reaction are redox reaction
  \(4BCl_{ 3 }(g)+3LiAl{ H }_{ 4 }(s)\longrightarrow 2{ B }_{ 2 }{ H }_{ 6 }(g)+3LiCl(s)+3AlC{ l }_{ 3 }(s)\)

• 3)

  Justify that the following reaction are redox reaction
  \(2k(s)+{ F }_{ 2 }(g)\longrightarrow 2K^{ + }{ F }^{ - }(s)\)

• 4)

  Justify that the following reaction are redox reaction
  \(4N{ H }_{ 3 }(g)+5{ O }_{ 2 }(g)\longrightarrow 4NO(g)+6H_{ 2 }O(g)\)

• 5)

  Using electron transfer concept, identify the oxidant and reductant in the redox reaction.
  (a) Zn(s) +2H⁺(aq)\(\rightarrow\) Zn²⁺(aq) +H₂(g)
  (b) 2[Fe(CN)₆]^4-(aq)+H₂O₂(aq)+2H⁺(aq)→2[Fe(CN)₆]^-3(aq)+2H₂O(l)
  (c) 2[Fe(CN)₆]^3-(aq)+2OH^-(aq)+H₂O₂(aq)→2[Fe(CN)₆]^4-(aq)+O₂(g)+2H₂O(l)
  (d) \(Br{ O }_{ 3 }^{ - }(aq)+{ F }_{ 2 }(g)+2O{ H }^{ - }(aq)\rightarrow Br{ O }_{ 4 }^{ - }(aq)+2{ F }^{ - }(aq)+{ H }_{ 2 }O(l)\)
  (e) \(2NaCl{ O }_{ 3 }(aq)+{ I }_{ 2 }(aq)\rightarrow 2NaCl{ O }_{ 3 }(aq)+{ cl }_{ 2 }(g)\)

11th CBSE Chemistry - Equilibrium Five Mark Model Questions - by Amit Pandya - Varanasi - Oct 03, 2019 - View & Read

• 1)

  Calculate degree of hydrolysis,

• 2)

  Calculate the pH of a buffer which is 0.1 M in acetic acid and 0.15 M in sodium acetate. Given that the ionisation costants of acetic acid is 1.75 x 10^-5. Also calculate the change in pH of the buffer if to 1L of the buffer 1 cc of 1 M NaOH are added.

• 3)

  Calculate the hydrogen ion concentration in the following biological fluids whose pH are given below:
  (a) Human muscle-fluid, 6.83
  (b) Human stomach fluid, 1.2
  (c) Human blood, 7.38
  (d) Human saliva, 6.4.

• 4)

  The p^H of milk, black coffee, tomato juice, lemon juice and egg white are 6.8,5.0,4.2,2.2 and 7.8 respectively. Calculate the corresponding hydrogen ion concentration in each.

• 5)

  On the basic of Le-Chatelier principle explain how temperature and pressure can be adjusted to increase the yield of ammonia in the following reaction.
  \({ N }_{ 2 }\left( g \right) +3{ H }_{ 2 }\left( g \right) \rightleftharpoons 2{ NH }_{ 3 }\left( g \right) \triangle H=192.38 \ KJ \ { mol }^{ -1 }\) What will be the effect of addition of argo to the above reaction mixture at constant volume?

CBSE 11th Chemistry - Classification of Elements and Periodicity in Properties Four and Five Marks Questions - by Ashutosh Saran - Gurgaon - Sep 30, 2019 - View & Read

• 1)

  The elements Z = 117 and 120 have not yet been discovered. In which family/group would you place these elements and also give the electronic configuration in each case.

• 2)

  Calculate the electronegativity of carbon if E_H-H = 104.2 kcal mol^-1, E_C-C =  83.1 kcal mol^-1,E_C-H = 98.8 kcal mol^-1, X_H = 2.1.

• 3)

  The first (∆_i H₁) and the second (∆_i H₂) ionization enthalpies (in kJ mol^–1) and the (∆_egH) electron gain enthalpy (in kJ mol^–1) of a few elements are given below:

  Elements	\({ \triangle }_{ i }{ H }_{ 1 }\)	\({ \triangle }_{ i }{ H }_{ 2 }\)	\({ \triangle }_{ eg }H\)
  I	520	7300	-60
  II	419	3051	-48
  III	1681	3374	-328
  IV	1008	1846	-295
  V	2372	5251	+48
  VI	738	1451	-40

  Which of the above elements is likely to be :
  (a) the least reactive element.
  (b) the most reactive metal.
  (c) the most reactive non-metal.
  (d) the least reactive non-metal.
  (e) the metal which can form a stable binary halide of the formula MX₂(X=halogen).
  (f) the metal which can form a predominantly stable covalent halide of the formula MX (X=halogen)?

• 4)

  Arrange the following in decreasing order of their van der Waals' radii CI, H, O, N.

• 5)

  Chemical reactivity of elements is highest at the two extremes of a period and is lowest in the center. Highly reactive elements do not occur in nature in free state, they usually occur in nature in free state, they usually occur in combined state. Some students are highly aggressive and keep on fighting with each other like highly reactive elements. Some students are sober and help each other and do not fight.
  (i) Elements of which group are most reactive?
  (ii) Which group elements are least reactive and why?
  (iii) What are the harmful effects of being aggressive?
  (iv) What values are possessed by sober people?
  (v) Which kind of people pick up fight, while driving on the road in case of accidents? What are its consequences? What should we do?

11th Standard CBSE Chemistry - Structure of Atom Four and Five Marks Questions - by Ashutosh Saran - Gurgaon - Sep 30, 2019 - View & Read

• 1)

  Which state of the triple ionised beryllium \((Be^{ 3+ })\) has the same orbit radius at that of the ground state of hydrogen atom?

• 2)

  The wavelength range of the visible spectrum extends from violet (400 nm) to red (750 nm). Express these wavelengths in frequencies (Hz). (1nm = 10^–9 m)

• 3)

  The number of electrons, protons and neutrons in a species are equal to 18, 16 and 16 respectively. Assign the proper symbol to the species.

• 4)

  The threshold frequency ν₀ for a metal is 7.0 ×10¹⁴ s^–1. Calculate the kinetic energy of an electron emitted when radiation of frequency ν =1.0 ×10¹⁵ s^–1 hits the metal.

• 5)

  A golf ball has a mass of 40g, and a speed of 45 m/s. If the speed can be measured within accuracy of 2%, calculate the uncertainty in the position.

11th Standard CBSE Chemistry - Some Basic Concept of Chemistry Four Marks and Five Marks Questions - by Ashutosh Saran - Gurgaon - Sep 30, 2019 - View & Read

• 1)

  Convert the following into basic units
  25365 mg.

• 2)

  At what temperature will both the Celsius and Fahrenheit scales read the same value ?

• 3)

  A measured temperature on Fahrenheit scale is 200^o F. What will this reading be on Celsius scale?

• 4)

  Express the following in the scientific notation
  (4.56 x 10³ + 2.62 x 10²)

• 5)

  Express the following in the scientific notation
  (9.87 x 10^-3 - 2.26 x 10^-4)

11th Standard CBSE Chemistry - Environmental Chemistry Three Marks Questions - by Ashutosh Saran - Gurgaon - Sep 27, 2019 - View & Read

• 1)

  What are pesticides and herbicides? Explain giving examples.

• 2)

  How is the temperature effected as we go up the earth's surface? Explain

• 3)

  What do you mean by ozone hole? What are its consequences?

• 4)

  Sonu and Nilesh were friends. In winters, one day when they were going to school at 10:00 am Sonu felt irritation in his eyes and throat. He was also unable to breath.
  Nilesh immediately took him to a doctor. Doctor gave him the proper remdy. When he became well, Nilesh asked reason for this Doctor answered him satisfactorily.
  (i) Can you guess what reason was given by the doctor for the illness of Sonu.
  (ii) Why such kind of polluting atmospheric change occurs?
  (iii) What should be done to prevent the formation of smog?
  (iv) What values are possessed by Nilesh?

• 5)

  Explain the tropospheric pollution in 100 words?

CBSE 11th Chemistry - Hydrocarbons Three Marks Questions - by Ashutosh Saran - Gurgaon - Sep 27, 2019 - View & Read

• 1)

  How do you account for the formation of ethane during chlorination of methane ?

• 2)

  For the following compounds, write structural formulas and IUPAC names for all possible isomers having the number of double or triple bond as indicated :
  (a) C₄H₈ (one double bond)
  (b) C₅H₈ (one triple bond)

• 3)

  An alkene ‘A’ contains three C – C, eight C – H σ bonds and one C – C π bond. ‘A’ on ozonolysis gives two moles of an aldehyde of molar mass 44 u. Write IUPAC name of ‘A’.

• 4)

  Why is benzene extra ordinarily stable though it contains three double bonds?

• 5)

  What are the necessary conditions for any system to be aromatic?

CBSE 11th Chemistry - Organic Chemistry: Some Basic Principles and Techniques Three Marks Questions - by Ashutosh Saran - Gurgaon - Sep 27, 2019 - View & Read

CBSE 11th Chemistry - The p-block Elements Three Marks Questions - by Ashutosh Saran - Gurgaon - Sep 27, 2019 - View & Read

• 1)

  A certain salt X, gives the results Borax swells up to a glassy mass on strong heating.
  Is swells up to a glassy material Y on strong heating

• 2)

  Explain the following.
  Aluminium forms [AlF₆]^3- ion but boron does not form [BF₆]^3-ion.

• 3)

  Account for CO is poisonous.

• 4)

  Account for CO₂ is used in refrigeration.

• 5)

  What are electron deficient compounds? Are BCl₃ and SiCl₄ electron deficient species? Explain.

CBSE 11th Chemistry - The s-Block Elements Three Marks Questions - by Ashutosh Saran - Gurgaon - Sep 27, 2019 - View & Read

• 1)

  Compare the alkali metals and alkaline earth metals with respect to basicity of oxides

• 2)

  Present a comparative account of the alkali and akaline earth metals with respect to the following characteristics.
  Nature of oxides and their solubility in water

• 3)

  Present a comparative account of the alkali and akaline earth metals with respect to the following characteristics.
  solubility of oxosalt

• 4)

  Explain the Aluminium utensils should not be kept in water overnight.

CBSE 11th Chemistry - Hydrogen Three Marks Questions - by Ashutosh Saran - Gurgaon - Sep 27, 2019 - View & Read

• 1)

  If 1kg of a hard water sample contains 12 mg of CaCl₂ and 12mg of MgCl_2, then what will be the total hardness in terms of CaCO₃ Per 10⁶ parts by mass of water sample.

• 2)

  Write equations for the reactions
  Peroxydisulphuric acid is hydrolysed.

• 3)

  Calculate the volume strength of a 3% solution of \({ H }_{ 2 }O_{ 2 }\)

• 4)

  What are the advantages in using hydrogen as a fuel?

• 5)

  Why is hydrated barium peroxide used in the preparation of hydrogen peroxide instead of anhydrous barium peroxide?

11th Standard CBSE Chemistry - Redox Reactions Three Marks Questions - by Ashutosh Saran - Gurgaon - Sep 27, 2019 - View & Read

• 1)

  Suggest a list of the substances where carbon can exhibit oxidation states from –4 to +4 and nitrogen from –3 to +5.

• 2)

  Write formulas for the following compounds:
  (a) Mercury(II) chloride
  (b) Nickel(II) sulphate
  (c) Tin(IV) oxide
  (d) Thallium(I) sulphate
  (e) Iron(III) sulphate
  (f) Chromium(III) oxide

• 3)

  Whenever a reaction between an oxidising agent and a reducing agent is carried out, a compound of lower oxidation state is formed if the reducing agent is in excess and a compound of higher oxidation state is formed if the oxidising agent is in excess. Justify this statement giving three illustrations.

11th Standard CBSE Chemistry - Equilibrium Three Marks Questions - by Ashutosh Saran - Gurgaon - Sep 27, 2019 - View & Read

• 1)

  What is the minimum volume of water required to dissolve 1g of calcium sulphate at 298 K? (For calcium sulphate, K_sp is 9.1 x 10^-6).

• 2)

  The ionization constant of acetic acid is 1.74 × 10^–5. Calculate the degree of dissociation of acetic acid in its 0.05 M solution. Calculate the concentration of acetate ion in the solution and its pH.

• 3)

  An equilibrium mixture at 300K contains N₂ O₄ and NO₂ at .28 and 1.1 atm pressure respectively. If the volume of the container is doubled, calculate the new equilibrium pressure of two gases.

• 4)

  The ionization constant of dimethylamine is 5.4 × 10^–4. Calculate its degree of ionization in its 0.02M solution. What percentage of dimethylamine is ionized if the solution is also 0.1M in NaOH?

• 5)

  At 473K, equilibrium constant K_c for decomposition of phosphorus pentachloride Pcl₅ is \(8.3\times { 10 }^{ -3 }\) . If decomposition is depicted as, 
  \({ PCl }_{ 5 }(g)\leftrightharpoons { PCl }_{ 3 }(g)+{ Cl }_{ 2 }(g);\)
  \( \Delta H°=124.0 \ { kJmol }^{ -1 }\)
  What would be the effect on \({ K }_{ c } \) if (a) more PCl₅   is added (b) pressure is increased (c) the temperatured in increased ?

11th Standard CBSE Chemistry - Thermodynamics Three Marks Questions - by Ashutosh Saran - Gurgaon - Sep 27, 2019 - View & Read

• 1)

  A man takes a diet equivalent to 10000 kJ per day and does work, in expending his energy in all forms equivalent to 12500 kJ per day. What is change in internal energy per day?If the energy lost was stored as sucrose (1632 kJ pre 100g), how many days should it take to lose 2kg of his weight?(Ignore water loss)

• 2)

  The enthalpy of vaporization of liquid diethyl ether (C₂H₅)₂₀ is 26.0 KJ mol^-1 at its boiling point (35.0^oC). Calculate \(\triangle \)S^o for the conversion of Liquid to vapour and

• 3)

  Calculate the standard Gibbs energy change for the formation of propane at 298 K.
  3 C (graphite) + 4H₂(g) → C₃H₈ (g)
  \(\triangle _{ f }{ H }^{ o }for\quad propane,{ C }_{ 3 }{ H }_{ 8 }(g)=270.2J{ K }^{ -1 }{ mol }^{ -1 }\)
  \({ S }_{ m }^{ o }C(graphite)=5.70J{ K }^{ -1 }{ mol }^{ -1 }\)
  \( and \ { S }_{ m }^{ 0 }{ H }_{ 2 }(g)=130.7J{ K }^{ -1 }{ mol }^{ -1 }\)

• 4)

  The molar heat of formation of NH₄NO₃ (s) is -367.54 kJ and those of N₂ O(g) and H₂O(i) are + 81.46 kJ and -258.78 kJ respectively at 25^oC and 1.0 atmospheric pressure. Calculate \(\Delta \)H and \(\Delta \)U for the reaction.

• 5)

  Justify the following statements.
  (i) Reaction with \(\triangle \)G^o < 0 always have an equilibrium constant greater than 1.
  (ii) Many thermodynamically feasible reactions do not occur under ordinary conditions.
  (iii) At low temperatures, enthalpy change dominates the △△G expression and at high temperatures, it is the entropy which dominates the value of △G.

11th Standard CBSE Chemistry - State of Matter Five Mark Question Paper - by Amit Pandya - Varanasi - Sep 25, 2019 - View & Read

• 1)

  Explain
  The boiling point of a liquid rises on increasing pressure.

• 2)

  Explain
  The level of mercury in a capillary tube is lower than the level outside when a capillary tube inserted in the mercury.

• 3)

  Tea or coffee is sipped from a saucer when it is quite hot.

• 4)

  Calculate the total and average kinetic energy of 32 g methane molecules at 27^oC(R = 8.314 JK^-1 mol^-1 )

• 5)

  Nitrogen molecule(N₂ )has radius of about 0.2 nm. Assuming that nitrogen molecule is spherical in shape, calculate volume of a single molecule of N₂

11th Standard CBSE Chemistry - Thermodynamics Five Mark Question Paper - by Amit Pandya - Varanasi - Sep 25, 2019 - View & Read

• 1)

  An athlete is given 100g of glucose of energy equivalent to 1560 kJ. He utilises 50% of this gained energy in the event.In order to avoid storage of energy in the body, calculate the weight of water that would need to perspire.The enthalpy of vaporisation of water is 44 kJ mol^-1.

• 2)

  When 20.0 g of ammonium nitrate (NH₄NO₃) is dissolved in 125 g of water in a coffee cup calorimeter. (Treat heat capacity of water as the heat capacity of the calorimeter and its contents).

• 3)

  A chemist while studying the properties of gaseous CCl₂, a chlorofluorocarbon refrigerant, cooled a 1.25 g sample at a constant atmospheric pressure of 1.0 atm from 320 K to 293 K. During cooling, the sample volume decreased from 274 to 248 mL. Calculate \(\Delta\)H and \(\Delta\)U for the chlorofluorocarbon for this process. For CCl₂F₂, C_p = 80.7 J/(mol K).

• 4)

  A cylinder of gas supplied by a company is assumed to contain 14kg of butane.If a normal family requires 20000kj of energy per day for cooking, how long will the cylinder last?

• 5)

  If the air supplied to the burner is insufficient, a portion of gas escapes without combustion. Assuming that 25% of the gas is wasted due to this inefficiency, how long will the cylinder last (Heat of combustion of butane = 2658 kJ/mol)?

11th Standard CBSE Chemistry - Chemical Bonding and Molecular Structure Five Mark Question Paper - by Amit Pandya - Varanasi - Sep 24, 2019 - View & Read

• 1)

  Arrange the following in increasing order of ionic character  and also give the reason.
  NaCl, CaCl₂, MgCl_2, MgO.

11th Standard CBSE Chemistry - Classification of Elements and Periodicity in Properties Five Mark Question Paper - by Amit Pandya - Varanasi - Sep 24, 2019 - View & Read

• 1)

  Use the periodic table to answer the following questions.
  (a) Identify an element with five electrons in the outer subshell.
  (b) Identify an element that would tend to lose two electrons.
  (c) Identify an element that would tend to gain two electrons.
  (d) Identify the group having metal, non-metal, liquid as well as gas at the room temperature

• 2)

  Which elements have the following electronic configuration? (Use only the periodic table.)
  1s², 2s², 2p⁵

• 3)

  In p-block elements form acidic, basic and amphoteric oxides. Explain each property by giving two examples and also write the reactions of these oxides with water.

11th CBSE Chemistry - Structure of Atom Five Mark Question Paper - by Amit Pandya - Varanasi - Sep 23, 2019 - View & Read

• 1)

  Show that the circumference of the Bohr orbit for the hydrogen atom is an integral multiple of the de Broglie wavelength associated with the electron revolving around the orbit.

• 2)

  Calculate the energy required for the process
  \(He^{ + }\left( g \right) \longrightarrow { He }^{ 2+ }\left( g \right) +{ e }^{ - }\) 
  The ionization energy for the H atom in the ground state is 2.18 × 10^–18 J atom^–1

• 3)

  A beam of helium of atoms move with a velocity of \(2.0\times { 10 }^{ 3 }{ ms }^{ -1 }\) Find the wavelength of the particle constituting the beam. (h = 6.626 \(\times \)10^-34 Js).

• 4)

  List the quantum number (m_l and l) of electrons for 3d - orbital.
  Notes:
  l has the value 0 to (n - 1)
  m has the value -l to l
  The value of l never be equal to n or greater than it.

11th CBSE Chemistry - Some Basic Concept of Chemistry Five Mark Question Paper - by Amit Pandya - Varanasi - Sep 23, 2019 - View & Read

• 1)

  How many atoms of He are present in 52 \(\mu\) of He?

• 2)

  A lady purchases a ring from a jeweller with diamonds embedded into it. The jeweller tells that total diamond used in the ring is five carat. How much weight he should subtract from the weight of the ring to get the weight of gold?

• 3)

  Copper sulphate crystals contain 25.45% Cu and 36.07% H₂O. If the law of constant proportions is true then calculate the weight of Cu requires to obtain 40g of crystalline CuSo₄.

CBSE 11th Chemistry - State of Matter Three Marks Questions - by Ashutosh Saran - Gurgaon - Sep 21, 2019 - View & Read

• 1)

  A gas is enclosed in the room. The temperature, pressure, density, and the number of moles respectively are t \(^{o}\)C, p atm, g cm^-3 and n moles. What will be the values of pressure, temperature, density, and the number of moles in each compartment if the walls between the two compartments (say 1 and 2) are removed?

• 2)

  A 2 L flask contains 1.6g of methane and 0.5 g of hydrogen at 27^oC. Calculate the partial pressure of each gas in the mixture and also calculate the total pressure.

• 3)

  0.64 g of an oxide of sulphur occupies 0.224 L at 2 bars and 273^oC. Identify the compound.Also, find out the mass of one molecular of the gas.

• 4)

  The compression factor(compressibility factor) for one mole of a van der Waals gas at 0^oC and 100 atm pressure is found to be 0.5. Assuming that the volume of a gas molecule is negligible, calculate the van der Walas' constant a.

11th Standard CBSE Chemistry - Chemical Bonding and Molecular Structure Three Marks Questions - by Ashutosh Saran - Gurgaon - Sep 21, 2019 - View & Read

• 1)

  On the basis of molecular orbital theory what is similarly between (a) \({ F }_{ 2 },{ O }_{ 2 }^{ 2- }\)  ,(b) CO,N₂,NO⁺

11th Standard CBSE Chemistry Unit 3 Classification of Elements and Periodicity in Properties Three Marks Questions - by Ashutosh Saran - Gurgaon - Sep 20, 2019 - View & Read

• 1)

  Give the name and atomic number of the inert gas atom in which the total number of numbers of d-electrons is equal to the difference in numbers of total p and s electrons.

• 2)

  Can an element with atomic number 126, if discovered, be accommodated in the present set up of the long form of periodic table?

• 3)

  First member of each group of representative elements  ( i.e. sand p-block elements ) shows anomalous behaviour. Illustrate with two examples.

• 4)

  Arrange the following as stated. 'Decreasing order of electropositive character of Cu, Fe Mg'

11th Standard CBSE Chemistry Unit 2 Structure of Atom Three Marks Questions - by Ashutosh Saran - Gurgaon - Sep 20, 2019 - View & Read

• 1)

  Which of the following are isoelectronic species i.e., those having the same number of electrons?
  Na⁺,K⁺,Mg²⁺,Ca²⁺,S^2-,Ar

• 2)

  Write the complete symbol for the atom with the given atomic number (Z) and atomic mass (A)
  (i) Z = 17, A = 35.
  (ii) Z = 92, A = 233.
  (iii) Z = 4, A = 9.

11th Standard CBSE Chemistry - Some Basic Concept of Chemistry Three Marks Questions - by Ashutosh Saran - Gurgaon - Sep 20, 2019 - View & Read

• 1)

  To account for the atomic mass of nitrogen as 14.0067,\(\mu\) what should be the ratio of and atoms \({ 15 }_{ N }\)\({ 14 }_{ N }\) in natural nitrogen? (atomic mass of \({ 14 }_{ N }\) = 14.00307 \(\mu\) and \({ 15 }_{ N }\) = 15.001\(\mu\))

• 2)

  A compound contains 4.07% hydrogen, 24.27% carbon and 71.65% chlorine. Its molar mass is 98.96 g. What are its empirical and molecular formulas?

• 3)

  Convert the following into metre
  (i) 40 Em (thickness of Milky way galaxy)
  (ii) 1.4 Gm (diameter of Sun)
  (iii) 41 Pm (distance of nearest star)

CBSE 11th Chemistry - Environmental Chemistry Two Marks Questions - by Ashutosh Saran - Gurgaon - Sep 18, 2019 - View & Read

• 1)

  What could be the harmful effects of improper management of industrial and domestic solid waste in a city?

• 2)

  For dry cleaning in the place of tetrachloroethene, liquefied carbon dioxide with suitable detergent is an alternative solvent. What type of harm to the environment will be prevented by stopping use of tetrachloroethene? Will use of liquefied carbon dioxide with detergent be completely safe from the point of view of pollution. Explain.

• 3)

  What do you mean by primary and secondary pollutants of the air?

• 4)

  Which zone is known as ozonosphere?

• 5)

  Which main gases is responsible for damage in ozone layer?

11th Standard CBSE Chemistry - Hydrocarbons Two Marks Questions - by Ashutosh Saran - Gurgaon - Sep 18, 2019 - View & Read

• 1)

  Rotation around carbon-carbon single bond of ethane is not completely free. Justify the statement.

• 2)

  On converting benzene to toluene, state whether there will be a rise or fall in the melting point.

• 3)

  Why do you alkenes prefer to undergo electrophilic addition reaction while arenes prefer electrophilic substitution reactions? Explain.

• 4)

  Draw the cis and trans structures of hex-2-ene. Which isomer will have higher b.p. and why?

• 5)

  What effect does branching of an alkane chain has on its boiling point?

11th Standard CBSE Chemistry - Organic Chemistry: Some Basic Principles and Techniques Two Marks Questions - by Ashutosh Saran - Gurgaon - Sep 18, 2019 - View & Read

• 1)

  Give the common name of (a) methanol, (b) ethanol, (c) ethoxyethane, (d) ethanoic acid, (e) 1, 4 - dimethyl benzene.

• 2)

  How many \(\sigma\) and  \(\pi\) bonds are present in each of the following molecules?
  \(CH_{ 3 }-CH=CH-CH_{ 2 }-C\equiv CH\)

• 3)

  Identify the most stable species in the following set of ions giving reasons
  \(\overset { - }{ C } { H }_{ 3 },\overset { - }{ C } { H }_{ 2 }CI,\overset { - }{ C } { H }CI_{ 2 },\overset { - }{ C } CI_{ 3 }\)

• 4)

  Which bond is more polar in the following pairs of molecules:
  (a) H₃C - H or H₃C - Br
  (b) H₃C - NH₂ or H₃C - OH
  (c) H₃C - OH or H₃C - SH

• 5)

  What is meant by delocalization?

11th Standard CBSE Chemistry - The p-block Elements Two Marks Questions - by Ashutosh Saran - Gurgaon - Sep 18, 2019 - View & Read

• 1)

  Discuss the pattern of variation in the oxidation states of B to TI

• 2)

  How does electron deficient compound BF₃ achieve electronic saturation , i.e fully ooccupied outer electron shells?

• 3)

  Give one chemical reaction to show that Tin(II) chloride is a reducing agent.

• 4)

  Give reasons.
  Conc.HNO₃ can be transported in aluminium container.

• 5)

  Why does lime water turn milky when CO₂  is passed through it.

CBSE 11th Chemistry - The s-Block Elements Two Marks Questions - by Ashutosh Saran - Gurgaon - Sep 16, 2019 - View & Read

• 1)

  A white solid X is a compound of alkali metal. A piece of red litmus paper turns white when it is dipped into a freshly made aqueous solution of the white solid. Identify the white solid X.

• 2)

  Write the Lewis structure of O₂^- ion and find out oxidation state of each oxygen atom? What is the average oxidation state of oxygen in this ion?

• 3)

  Explain why can alkali and alkaline earth metals not be obtained by chemical reduction methods?

• 4)

  What happens when magnesium reacts with SO₂ gas ?

• 5)

  When alkali metals dissolves in liquid ammonia, the solution can acquire different colours.Explain the reason for. this type of colour change.

CBSE 11th Chemistry - Hydrogen Two Marks Questions - by Ashutosh Saran - Gurgaon - Sep 16, 2019 - View & Read

• 1)

  \({ H }_{ 2 }{ O }_{ 2 }\) is a better oxidising agent than water as discussed below. Explain.

• 2)

  Calculate the strength of 10 volume solution of hydrogen peroxide.

• 3)

  Explain the correct context in which the following terms are used diprotium.

• 4)

  Would you expect the hydrides of N, O and F to have lower boiling points than the hydrides of their subsequent group members? Give reasons.

• 5)

  How do you expect the metallic hydrides to be useful for hydrogen storage? Explain

11th Standard CBSE Chemistry - Redox Reactions Two Marks Questions - by Ashutosh Saran - Gurgaon - Sep 16, 2019 - View & Read

• 1)

  Balance the following equations in basic medium by ion electron and oxidation number methods and identify the oxidising agent and the reducing agent
  \(CI_{ 2 }O_{ 7 }(g)+H_{ 2 }O_{ 2 }(aq)\longrightarrow CIO_{ 2 }^{ - }(aq)+O_{ 2 }(g)\)

• 2)

  A solution of silver nitrate was stirred with iron rod.Will it cause any change in the concentration of silver and nitrate ions?

• 3)

  How many millimoles of potassium dichromate is required to oxidise 24mL of 0.5 M Mohr's salt solution in acidic medium?

• 4)

  Two half cells are AI³⁺ (aq) /AI and Mg²⁺ (aq)/Mg.The reduction potentials of these half-cells are -1.66 V and -2.36 V respectively. Calculate the cell potential. Write the cell reaction also. 

• 5)

  Assign oxidation number to the underlined elements in each of the following species - K₂MnO₄

11th Standard CBSE Chemistry - Equilibrium Two Marks Questions - by Ashutosh Saran - Gurgaon - Sep 16, 2019 - View & Read

• 1)

  How much volume of 0.1 M HAc should be added to 50 mL of 0.2 M HAc solution if we want to prepare a buffer solution of pH 4.91. Given pK_a for acetic acid is 4.76.

• 2)

  Which of the following reactions involve homogeneous equilibrium and which involve heterogeneous equilibrium?
  (i) \({ Ag }_{ 2 }O(s)+2HN{ O }_{ 3 }(aq)\rightleftharpoons 2{ Ag }NO_{ 3 }(aq)+{ H }_{ 2 }O(l)\)
  (ii) \(C(s)+CO_{ 2 }(g)\rightleftharpoons 2CO(g)\)
  (iii) \(CH_{ 3 }COOC_{ 2 }H_{ 5 }(aq)+{ H }_{ 2 }O(l)\rightleftharpoons CH_{ 3 }COOH(aq)+{ C }_{ 2 }{ H }_{ 5 }OH(aq)\)
  (iv) \(2SO_{ 2 }(g)+O_{ 2 }(g)\rightleftharpoons 2SO_{ 3 }(g)\)
  (v) \(2Cu\left( { NO }_{ 3 } \right) _{ 2 }(s)\rightleftharpoons 2Cuo(s)+4{ No }_{ 2 }(g)+{ O }_{ 2 }(g)\)
  (vi) \({ CH }_{ 3 }COO{ C }_{ 2 }{ H }_{ 5 }(aq)+{ H }_{ 2 }O(l)\rightleftharpoons { CH }_{ 3 }COOH(aq)+{ C }_{ 2 }{ H }_{ 5 }OH(aq)\)
  (vii) \({ Fe }^{ 3+ }(aq)+3{ OH }^{ - }(aq)\rightleftharpoons Fe(OH)_{ 3 }(s)\)
  (viii) \({ I }_{ 2 }(s)+5{ F }_{ 2 }(g)\rightleftharpoons 2I{ F }_{ 5 }(g)\)

• 3)

  Explain why pure liquids and solids can be ignored while writing the equilibrium constant expression?

CBSE 11th Chemistry - Thermodynamics Two Marks Questions - by Ashutosh Saran - Gurgaon - Sep 16, 2019 - View & Read

• 1)

  The enthalpy of a vaporisation of CCI₄ is 30.5 kJ mol^-1. Calculate the heat required for the vaporisation of 284g of CCI₄ at constant pressure (molar mass of CCI₄ =154 g mol^-1)

• 2)

  Calculate the number of kJ of heat necessary to raise the temperature of 60.0 g of aluminium from 35°C to 55°C. Molar heat capacity of Al is 24 J mol^–1 K^–1.

• 3)

  18.0 g water completely vaporises at 100 ^oC and 1 bar pressure and the enthalpy change in the process is 40.79 KJ mol^-1. What  will be the enthalpy change for vaporising two moles of water under the same conditions? What is the standard enthalpy of vaporisation for water?

• 4)

  Although heat is path function but heats absorbed by the system under certain specific conditions is independent of path. what are those conditions? Explain when pressure remains constant.

CBSE 11th Chemistry - State of Matter Two Marks Questions - by Ashutosh Saran - Gurgaon - Sep 14, 2019 - View & Read

• 1)

  Use the information and data given below to answer the question, stronger intermolecular forces result in higher boiling point.
  Strength of London forces increases with the number of electrons in the molecules. Boiling point of HF, HCI, HBr, and HI are 293 K, 189 K, 206 K and 238 K respectively.
  Looking at the trend of boiling points of HCI, HBr, and HI, explain out of dipole-dipole interaction and London interaction, which one is predominant here.

• 2)

  Calculate the kinetic energy of 2g of oxygen at -23^oC

• 3)

  The density of liquid CO₂ at room temperature is 0.8 g cm^-3 .how large a cartridge of liquid CO₂ must be provided to inflate a life jacket of 4 L capacity at STP?

• 4)

  It is desired to increase the volume of 800 mL of a gas by 20% keeping the pressure constant. To what temperature the gas must be heated if the initial temperature is 22^oC?

• 5)

  150 mL of a gas at NTP were taken to 20^oC and 0.96 bar pressure. What is the change in volume of the gas?

11th CBSE Chemistry - Chemical Bonding and Molecular Structure Two Mark Questions - by Ashutosh Saran - Gurgaon - Sep 14, 2019 - View & Read

• 1)

  Arrange the bonds in order of increasing ionic character in the molecules: LiF, K₂O , N₂, SO₂ and ClF₃ .

• 2)

  Arrange the following bonds in order of increasing ionic character giving reason. N-H, F-H, C-H and O-H

• 3)

  Arrange the following in order of decreasing bond angle, giving reason NO₂, \(NO_{ 2 }^{ + }\) and \(NO_{ 2 }^{ - }\)

• 4)

  Explain the shape of BrF₅

CBSE 11th Chemistry Unit 3 Classification of Elements and Periodicity in Properties Two Marks Questions - by Ashutosh Saran - Gurgaon - Sep 14, 2019 - View & Read

• 1)

  Which important property did Mendeleev use to classify the elements in his periodic table and did he stick to that?

• 2)

  All transition elements are d-block elements, but all d-block elements are not transition elements. Explain.

• 3)

  List the factors that can influence the ionic radius of an element.

• 4)

  Show by a chemical reaction with water that Na₂O is a basic oxide and Cl₂O₇ is an acidic oxide.

CBSE 11th Chemistry - Structure of Atom Two Marks Questions - by Ashutosh Saran - Gurgaon - Sep 14, 2019 - View & Read

• 1)

  Why does the charge to mass ratio of positive rays depend on the residual gas in the discharge tube? Why is the charge to mass ratio of all cathode rays are same?

• 2)

  Calculate energy of one mole of photons of radiation whose frequency is 5 x 10¹⁴ HZ.

• 3)

  In astronomical observations, signals observed from the distant stars are generally weak. If the photon detector receives a total of 3.15 × 10^–18 J from the radiations of 600 nm, calculate the number of photons received by the detector.

• 4)

  Calculate wave number of the line having frequency 5 x 10¹⁶ Hz.

• 5)

  Calculate the energy of one mole of the photons of a beam of light having wavelength 25.0 \(\mu \)m.

11th Standard CBSE Chemistry Unit 1 Some Basic Concept of Chemistry Two Mark Questions - by Ashutosh Saran - Gurgaon - Sep 14, 2019 - View & Read

• 1)

  The reactant which is entirely consumed in reaction is known as limiting reagent. In the reaction 2A + 4B \(\Rightarrow\) 3C + 4D, when 5 moles of A react with 6 moles of B, then calculate the amount of C formed?

• 2)

  The water level in a metric measuring cup is 0.75 L before the addition of a pebble weighing 150 g. The water level after submerging the pebble is 0.82 L. Determine the density of the pebble.

• 3)

  One of the statements of Dalton's atomic theory is given below "compounds are formed when atoms of different elements combine in a fixed ratio". Which laws of chemical combination is not related to this statement?

CBSE 11th Chemistry Unit 14 Environmental Chemistry Book Back Questions - by Ashutosh Saran - Gurgaon - Sep 07, 2019 - View & Read

• 1)

  Why does water covered with excessive algae growth become polluted?

• 2)

  In what regions of the atmosphere,the temperature increases with altitude and in which regions it decreases?

• 3)

  Name three natural sources of air pollution.

• 4)

  What are viable and non-viable particulates?

• 5)

  What is the nature of 'London smog' and why?

CBSE 11th Chemistry Unit 13 Hydrocarbons Book Back Questions - by Ashutosh Saran - Gurgaon - Sep 07, 2019 - View & Read

CBSE 11th Chemistry Unit 12 Organic Chemistry: Some Basic Principles and Techniques Book Back Questions - by Ashutosh Saran - Gurgaon - Sep 07, 2019 - View & Read

• 1)

  In the organic compound CH₂=CH-CH₂-CH₂-C\(\equiv \)CH,  the pair of hydridised orbitals involved in the formation of: C₂ - C₃ bond is _____.

• 2)

  The reaction: CH₃CH₂I + KOH _(aq) \(\rightarrow\)CH₃CH₂OH + KI is classified as :________.

• 3)

  What are primary and secondary suffixes as applied to IUPAC nomenclature?

• 4)

  How many σ and π bonds are present in each of the following molecules?
  (a) HC≡CCH=CHCH₃
  (b) CH₂=C=CHCH₃

CBSE 11th Chemistry Unit 11 The p-block Elements Book Back Questions - by Ashutosh Saran - Gurgaon - Sep 07, 2019 - View & Read

• 1)

  What is the formula of kernite, an ore of boron?

• 2)

  Are all the B-H bonds in diborane equivalent? 

CBSE 11th Chemistry - The s-Block Elements Book Back Questions - by Ashutosh Saran - Gurgaon - Sep 06, 2019 - View & Read

• 1)

  Which of the alkali metal is having least melting point?

• 2)

  Which one of the following alkali metals give hydrated salts?

• 3)

  Which one of the following alkaline earth metal carbonates is thermally most stable

• 4)

  State as to why a solution of Na₂CO₃ is alkaline?

• 5)

  The second ionisation enthalpy of calcium is more that of first and yet calcium forms MgCI₂ not MgCL. why?

CBSE 11th Chemistry - Hydrogen Book Back Questions - by Ashutosh Saran - Gurgaon - Sep 06, 2019 - View & Read

• 1)

  Suggest a method to show the electronegative nature of hydrogen.

• 2)

  How can saline hydrides remove traces of water from organic compounds?

• 3)

  Explain why beryllium forms a covalent hydride while calcium forms an iconic hydride.

• 4)

  Name the isotope of hydrogen which is commonly used as a tracer in organic reactions.

• 5)

  Name the constituents of water gas.

11th Standard CBSE Chemistry Unit 8 Redox Reactions Book Back Questions - by Ashutosh Saran - Gurgaon - Sep 05, 2019 - View & Read

• 1)

  Does the oxidation number of an element in any molecule or any polyatomic ion represent the actual charge on it?

11th Standard CBSE Chemistry Unit 7 Equilibrium Book Back Questions - by Ashutosh Saran - Gurgaon - Sep 05, 2019 - View & Read

• 1)

  A tank is full of water. Water is coming in as well as going out at same rate. What will happen to level of water in a tank? What is name given to such a state?

• 2)

  What is the expression for \({ k }_{ sp } \ of \ { Ag }_{ 2 }Cr{ 0 }_{ 4 }?\)

• 3)

  Under the conditions is a substance precipitated from its solution?

• 4)

  pK_a  value of acids A,B,C,D are 1.5, 3.5, 2.0 and 5.0.Which of them is strongest acid?

11th Standard CBSE Chemistry Unit 6 Thermodynamics Book Back Questions - by Ashutosh Saran - Gurgaon - Sep 04, 2019 - View & Read

• 1)

  Choose the correct answer. A thermodynamic state function is a quantity _______.

• 2)

  A reaction, A + B → C + D + q is found to have a positive entropy change. The reaction will be _______.

• 3)

  As per the available data: ______.

• 4)

  In the equation, \({ N }_{ 2 }(g)+3{ H }_{ 2 }(g)\rightleftharpoons 2N{ H }_{ 3 }(g)\) what would be the sign of work done?

• 5)

  At 1 atm will the \({ \triangle }_{ f }{ H }^{ \circ }\) be zero for Cl₂(g) and Br₂ (g)? Explain.

11th Standard CBSE Chemistry Unit 5 State of Matter Book Back Questions - by Ashutosh Saran - Gurgaon - Sep 04, 2019 - View & Read

• 1)

  One of the assumptions of kinetic theory of gases states that "there is no force of attraction between the molecules of a gas "How far is this statement correct?Is it possible to liquefy an ideal gas? Explain.

• 2)

  A gas that follows Boyle's law, Charle's law and Avogadro's law is called an ideal gas.Under what condition a real gas would behave ideally?

• 3)

  Explain why temperature of a boiling liquid remains constant?

• 4)

  Explain the physical significance of van derWaals' parameters.

• 5)

  What would have happened to the gas if the molecular collision were not elastic?

11th Standard CBSE Chemistry Unit 4 Chemical Bonding and Molecular Structure Book Back Questions - by Ashutosh Saran - Gurgaon - Sep 03, 2019 - View & Read

• 1)

  Why axial bonds of PCI₅ are longer than equatorial bonds?

11th Standard CBSE Chemistry Unit 3 Classification of Elements and Periodicity in Properties Book Back Questions - by Ashutosh Saran - Gurgaon - Sep 03, 2019 - View & Read

• 1)

  Why were the names eka-aluminium and eka-silicon given to gallium and germanium by Mendeleev?

• 2)

  Why do elements in the same group have similar physical and chemical properties?

• 3)

  A boy has reported the radii of Cu,Cu⁺ and Cu²⁺ as 0.096 nm,0.122 nm and 0.072 nm respectively.However, it has been noticed that he interchanged the values by mistake. Assign the correct values to different species.

• 4)

  Four elements have the following first ionisation enthalpies ( in kJ mol^-1); 869, 941, 1191 and 1142. The elements, in random order, are Se, Br, Te and I. Which element has an ionisation enthalphy of 869 kJ mol^-1 and 1142 kJmol^-1 respectively?

• 5)

  Explain why chlorine can be converted into chloride ion more easily as compared to fluoride ion from fluorine.

11th Standard CBSE Chemistry Unit 2 Structure of Atom Book Back Questions - by Ashutosh Saran - Gurgaon - Aug 31, 2019 - View & Read

• 1)

  What is the experimental evidence in support of the idea that electronic energies in an atom are quantised?

• 2)

  Which two discoveries put strong challenge to the Bohr model?

• 3)

  The magnitude of charge on the electron is \(4.8\times { 10 }^{ -10 }\) esu. What is the charge on the nucleus of a helium atom?

• 4)

  What physical meaning is attributed to the square of the absolute value of wave function \(|\psi |^{ 2 }\)?

• 5)

  An electron is in one of the 3d orbitals. Give the possible values of n, l and ml for this electron.

11th Standard CBSE Chemistry Unit 1 Some Basic Concept of Chemistry Book Back Questions - by Ashutosh Saran - Gurgaon - Aug 30, 2019 - View & Read

• 1)

  The empirical formula of sucrose is _______.

• 2)

  The number of significant figures in 0.0101 is _______.

• 3)

  The number of grams of oxygen in 0.10 mol of Na₂CO₃· 10H₂O is _______.

• 4)

  The mass of an atom of nitrogen is _______.

• 5)

  Using the unit conversion factor, express 1.54mm s^-1 into pm \(\mu \)s^-1.

11th Standard CBSE Chemistry Unit 9 Hydrogen One Mark Question and Answer - by Ashutosh Saran - Gurgaon - Aug 29, 2019 - View & Read

• 1)

  Hydrogen gas is generally prepared by the

• 2)

  Hydrogen peroxide is used as

• 3)

  Water may be softened using

• 4)

  On treatment of hard water with zeolite, sodium ions get exchanged with

• 5)

  Calgon, which is used as a water softener, has the formula

11th Standard CBSE Chemistry Unit 8 Redox Reactions One Mark Question and Answer - by Ashutosh Saran - Gurgaon - Aug 29, 2019 - View & Read

• 1)

  Among the following molecules, in which does bromine show the maximum oxidation number?

• 2)

  Which of the following halogens do not exhibit a positive oxidation number in their compounds?

• 3)

  Which of the following is most powerful oxidizing agent in the following

• 4)

  On the reaction 2Ag + 2H₂SO₄ \(\rightarrow\) Ag₂So₄ + 2H₂O+S_O2  sulphuric acid acts as ______.

• 5)

  The oxidation number of the carboxylic carbon atom in CH₃ COOH is ______.

11th Standard CBSE Chemistry Unit 7 Equilibrium One Mark Question and Answer - by Ashutosh Saran - Gurgaon - Aug 29, 2019 - View & Read

• 1)

  The equilibrium expression, K_c= [CO₂] represents the reaction.

• 2)

  Hydrogen molecule (H₂) can be dissociated into hydrogen atoms (H). Which one of the following changes will not increase the number of atoms present at equilibrium?

• 3)

  A catalyst will increase the rate of a chemical reaction by ______.

• 4)

  What is the correct expression for the representation of the solubility product constant of Ag₂ CrO₄ ?

11th Standard CBSE Chemistry Unit 6 Thermodynamics One Mark Question with Answer - by Ashutosh Saran - Gurgaon - Aug 28, 2019 - View & Read

• 1)

  Choose the correct answer. A thermodynamic state function is a quantity _______.

• 2)

  For the process to occur under adiabatic conditions, the correct condition is:_______.

• 3)

  As per the available data: ______.

• 4)

  Thermodynamics is applicable to ______.

• 5)

  An isochoric process takes place at constant ______.

11th Standard CBSE Chemistry Unit 5 State of Matter One Mark Question with Answer Key - by Ashutosh Saran - Gurgaon - Aug 28, 2019 - View & Read

• 1)

  For one mole of a gas, the ideal gas equation is

• 2)

  The cleansing action of soaps and detergents is due to

• 3)

  In van der Waals equation of state for a non-ideal gas the net force of attaction among the molecules is given by

• 4)

  The compressibility factor, z for an ideal gas is

• 5)

  Which of the following gases will have the lowest rate of diffusion?

11th Standard CBSE Chemistry Unit 4 Chemical Bonding and Molecular Structure One Mark Question and Answer - by Ashutosh Saran - Gurgaon - Aug 27, 2019 - View & Read

• 1)

  A co-ordinate bond is formed by ______.

• 2)

  The species CO, CN^- and N₂ are ______.

• 3)

  The axial overlap between the two orbitals leads to the formation of a: ______.

• 4)

  In SO₂ molecule, S atom is: ______.

• 5)

  A molecule or ion is stable if: ______.

11th CBSE Chemistry Unit 3 Classification of Elements and Periodicity in Properties One Mark Question with Answer Key - by Ashutosh Saran - Gurgaon - Aug 26, 2019 - View & Read

• 1)

  The highest ionization energy is exhibited by _____.

• 2)

  Which of the following oxides is neutral?

• 3)

  Which of the following is arranged in order of increasing radius?

• 4)

  What is the electronic configuration of the elements of group 14?

• 5)

  Among the following elements, which has the least electron affinity?

11th CBSE Chemistry Unit 2 Structure of Atom One Mark Question Paper - by Ashutosh Saran - Gurgaon - Aug 24, 2019 - View & Read

• 1)

  Cathode rays are deflected by _______.

• 2)

  The Balmer series in the spectrum of hydrogen atom falls in _______.

• 3)

  The energy needed to remove a single electron (most loosely bound) from an isolated gaseous atom is called _______.

• 4)

  The maximum number of electrons in a sub-shell is given by the equation _______.

• 5)

  If the value of azimuthal quantum number is 2, what will be the values for magnetic quantum number?

11th CBSE Unit 1 Some Basic Concept of Chemistry One Mark Question Paper - by Ashutosh Saran - Gurgaon - Aug 23, 2019 - View & Read

• 1)

  One mole of CO₂ contains _______.

• 2)

  5.6 litres of oxygen at NTP is equivalent to _______.

• 3)

  Which of the following has the highest mass?

• 4)

  The number of significant figures in 0.0101 is _______.

• 5)

  The number of grams of oxygen in 0.10 mol of Na₂CO₃· 10H₂O is _______.

11th CBSE Chemistry The p-block Elements Model Question Paper - by Ashutosh Saran - Gurgaon - Aug 20, 2019 - View & Read

• 1)

  Which of the following compound is an important catalyst as well as a Lewis acid?

• 2)

  Silicon carbide (SiC) is known as

• 3)

  Which of the following is a purely acidic oxide?

• 4)

  Which of the following molecules have zero dipole moment?

• 5)

  Silicon shows a diagonal relation with

11th CBSE Chemistry The s-Block Elements Model Question Paper - by Ashutosh Saran - Gurgaon - Aug 19, 2019 - View & Read

• 1)

  Which one of the following alkali metals give hydrated salts?

• 2)

  The reducing property of alkali metals follows the order

• 3)

  Lithium shows a diagonal relationship with

• 4)

  The oxide of which of the following metals is amphoteric?

• 5)

  Hydrides as well as halides of alkaline earth metals tend to polymerize

11th CBSE Chemistry Hydrogen Model Question Paper - by Ashutosh Saran - Gurgaon - Aug 19, 2019 - View & Read

• 1)

  Hydrogen gas is generally prepared by the

• 2)

  On treatment of hard water with zeolite, sodium ions get exchanged with

• 3)

  The higher density of water than that of ice is due to

• 4)

  Zeolite is

• 5)

  The decomposition of H₂O₂ is retarded by

11th Standard CBSE Chemistry Redox Reactions Model Question Paper - by Ashutosh Saran - Gurgaon - Aug 13, 2019 - View & Read

• 1)

  On the reaction 2Ag + 2H₂SO₄ \(\rightarrow\) Ag₂So₄ + 2H₂O+S_O2  sulphuric acid acts as ______.

• 2)

  When methane is burnt in oxygen to produce CO₂ and H₂0 the oxidation number of carbon changes by ______.

• 3)

  Which of the following are not redox reactions?

• 4)

  Which one among the following is not example of autoredox reaction?

• 5)

  In the ethylene molecule the two carbon atoms have the oxidation numbers.

11th Standard CBSE Chemistry Unit 7 Equilibrium Model Question Paper - by Ashutosh Saran - Gurgaon - Aug 03, 2019 - View & Read

• 1)

  The equilibrium expression, K_c= [CO₂] represents the reaction.

• 2)

  In a closed system
  A(S) ⇌ 4 B(g) + 3 C(g)
  If partial pressure of C is doubled, then partial pressure of B will be _____.

• 3)

  What effect does a catalyst have on the equilibrium position of a reaction?

• 4)

  A chemist dissolves an excess of BaSO₄ in pure water at 25°C if its K_sp = 1 x 10^-10 what is the concentration of barium in the water?

• 5)

  If in a mixture where Q = k is combined, then what happens?

11th CBSE Chemistry Unit 6 Thermodynamics Model Question Paper - by Ashutosh Saran - Gurgaon - Jul 31, 2019 - View & Read

• 1)

  Choose the correct answer. A thermodynamic state function is a quantity _______.

• 2)

  A reaction, A + B → C + D + q is found to have a positive entropy change. The reaction will be _______.

• 3)

  As per the available data: ______.

• 4)

  Thermodynamics is applicable to ______.

• 5)

  An isochoric process takes place at constant ______.

11th CBSE Chemistry Unit 5 State of Matter Important Question Paper - by Ashutosh Saran - Gurgaon - Jul 30, 2019 - View & Read

• 1)

  For one mole of a gas, the ideal gas equation is

• 2)

  Viscosity of a liquid is a measure of

• 3)

  The cleansing action of soaps and detergents is due to

• 4)

  The compressibility factor, z for an ideal gas is

• 5)

  Which of the following gases will have the lowest rate of diffusion?

11th Standard CBSE Chemistry Unit 4 Chemical Bonding and Molecular Structure Important Question Paper - by Ashutosh Saran - Gurgaon - Jul 27, 2019 - View & Read

• 1)

  A co-ordinate bond is formed by ______.

• 2)

  The species CO, CN^- and N₂ are ______.

• 3)

  The molecule Ne₂ does not exist because ______.

• 4)

  Which one is diamagnetic among NO⁺ , NO and NO^-?

• 5)

  sp³, sp² and sp hybridized carbon atom, the p character is maximum in:______.

11th Standard CBSE Chemistry Unit 3 Classification of Elements and Periodicity in Properties Important Question Paper - by Ashutosh Saran - Gurgaon - Jul 26, 2019 - View & Read

• 1)

  The highest ionization energy is exhibited by _____.

• 2)

  Which of the following oxides is neutral?

• 3)

  Which of the following is arranged in order of increasing radius?

• 4)

  What is the electronic configuration of the elements of group 14?

• 5)

  Among the following elements, which has the least electron affinity?

11th CBSE Chemistry Unit 2 Structure of Atom Important Question Paper - by Ashutosh Saran - Gurgaon - Jul 25, 2019 - View & Read

• 1)

  Cathode rays are deflected by _______.

• 2)

  In a sodium atom (atomic number = 11 and mass number = 23) and the number of neutrons is _______.

• 3)

  The Balmer series in the spectrum of hydrogen atom falls in _______.

• 4)

  The idea of stationary orbits was first given by _______.

• 5)

  de Broglie equation is _______.

11th CBSE Chemistry Unit 1 Some Basic Concept of Chemistry Important Question Paper - by Ashutosh Saran - Gurgaon - Jul 25, 2019 - View & Read

• 1)

  One mole of CO₂ contains _______.

• 2)

  5.6 litres of oxygen at NTP is equivalent to _______.

• 3)

  How many grams are contained in 1 gram atom of Na?

• 4)

  12 g of Mg will react completely with an acid to give: _______.

• 5)

  Which of the following has the highest mass?

11th Chemistry Model Question Paper 8 - by ADMIN-ENGLISH - Apr 12, 2018 - View & Read

11th Chemistry Model Question Paper 7 - by ADMIN-ENGLISH - Apr 12, 2018 - View & Read

Thermodynamics - Important Questions Model Paper 2 In 11th Chemistry - by ADMIN-ENGLISH - Apr 12, 2018 - View & Read

S - Block Elements - Important Questions Model Paper 2 In 11th Chemistry - by ADMIN-ENGLISH - Apr 12, 2018 - View & Read

P - Block Elements - Important Questions Model Paper 2 In 11th Chemistry - by ADMIN-ENGLISH - Apr 12, 2018 - View & Read

Structure Of Atom - Important Questions Model Paper In 11th Chemistry - by ADMIN-ENGLISH - Apr 12, 2018 - View & Read

State Of Matter - Important Questions Model Paper 2 In 11th Chemistry - by ADMIN-ENGLISH - Apr 12, 2018 - View & Read

Some Basic Concept Of Chemistry - Important Questions Model Paper In 11th Chemistry - by ADMIN-ENGLISH - Apr 11, 2018 - View & Read

Redox Reactions - Important Questions Model Paper 2 In 11th Chemistry - by ADMIN-ENGLISH - Apr 11, 2018 - View & Read

Organic Chemistry: Some Basic Principles And Techniques - Important Questions Model Paper In 11th Chemistry - by ADMIN-ENGLISH - Apr 11, 2018 - View & Read

Hydrogen - Important Questions Model Paper 2 In 11th Chemistry - by ADMIN-ENGLISH - Apr 11, 2018 - View & Read

Hydrocarbons - Important Questions Model Paper 2 In 11th Chemistry - by ADMIN-ENGLISH - Apr 11, 2018 - View & Read

Equilibrium - Important Questions Model Paper 2 In 11th Chemistry - by ADMIN-ENGLISH - Apr 11, 2018 - View & Read

Environmental Chemistry - Important Questions Model Paper 2 In 11th Chemistry - by ADMIN-ENGLISH - Apr 11, 2018 - View & Read

Classification Of Elements And Periodicity - Important Questions Model Paper In 11th Chemistry - by ADMIN-ENGLISH - Apr 11, 2018 - View & Read

Chemical Bonding And Molecular Structure - Important Questions Model Paper In 11th Chemistry - by ADMIN-ENGLISH - Apr 11, 2018 - View & Read